Thi thử VSTEP – 10 Bài Reading Test 4 Part 2

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 3
Questions 21-30

Despite modern society’s heavy dependence on fossil fuels for energy, most people are aware that the supply of these fuels is finite. As oil, in particular, becomes more costly and difficult to find, researchers are looking at alternative energy sources, including solar, wind, and even nuclear power. But which substitute – if any – is the right one?

Solar
Solar panels catch energy directly from the sun and convertitinto electricity. One of the world’s largest solar power stations is located near Leipzig, Germany, where more than 33,000 solar panels have the capacity to generate enough energy to power about 1,800 homes. But unlike the burning of fossil fuels, the process used to create all that solar energy produces noemissions.

Today, however, solar power provides less than one percent of the world’s energy, primarily because the cost of the panels is still very high. And price is only one issue. Clouds and darkness also cause solar panels to produce less energy, which requires one to have additional power sources (such as batteries) available.

Some scientists think the solution to this problem can be found in space – which they say is the ideal place to gather energy from the sun. With no clouds and no nighttime, a space-based solar power station could operate constantly producing continuous, clean energy which is cheaper than other fuels and sufficient for everyone on Earth.

Wind
Wind – the fastest-growing alternative energy source – is another way of collecting energy from the sun. Wind is caused by the sun’s heat rather than its light, and therefore, unlike solar power, it works well even on cloudy days.

All over Europe, incentives designed to decrease the dependence on oil and coal have led to a steep increase in wind-powered energy. Today, Europe leads the world in wind power, producing almost 35,000 megawatts, the equivalent of 35 large coal-powered plants. North America remains a distant second, producing just over 7,000 megawatts.

Despite its success, some oppose wind power development, saying the turbines are both noisy and ugly. There are other challenges, too. If the wind doesn’t blow, the turbines are not able to produce adequate energy. In contrast, a strong wind can create too much power leading the energy company to sell the extra power at a much-reduced rate.

What’s needed for both wind and solar is a way to store a large energy surplus. However, most systems are still decades away from making this a reality. On the plus side, both wind and solar enable people to generate their own energy where they live: People can have their own windmills or solar panels, with batteries for calm days.

Nuclear
In the 1970s, nuclear was seen as the main energy alternative because of its cheap production and no carbon emissions. For a number of years in the 1980s and ‘90s, however, use of nuclear power declined due to accidents, concerns about nuclear waste storage and disposal, and high construction costs. However, nowadays worldwide, about 432 plants now generate 13 percent of the planet’s electric power, and some countries have invested heavily in nuclear energy. France, for instance, gets three quarters of its electricity from nuclear power, the highest of any country. China has started to build one or two new plants a year, and India has also begun to utilize nuclear energy on a large scale.

In the end, is any of these sources alone the answer to our current energy problems? The short answer is no, but used in some combination – along with other power sources – we may find ways to reduce and eventually eliminate our dependence on fossil fuels.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.

PASSAGE 4
Questions 31-40

In the 1966 science-fiction filmFantastic Voyage, a team of scientists and doctors are shrunk and injected into the body of an injured man to save his life. The tiny crew travels through the body’s dangerous environment to locate and repair the damaged part of the man’s body. Eventually, the group manages to complete their task and the man awakens, fully cured.

[A] But what if it were possible to cure a disease like cancer using tiny particles injected into a person – particles that would not only find the cancer, but also destroy it without harming anything else in the body? Although it may seem like science fiction, tools like this are now being developed and may, in fact, become common in the near future – thanks to research currently being done in the field of nanotechnology. The main thing to know about nanotechnology is that it’s small – really small. The prefixnanorefers to a nanometer, which is one-billionth of a meter. A comma on a page of a book or magazine, for instance, may be more than half a million nanometers wide. [B]

Researcher Ted Sargent, a leader in the field of nanotechnology, describes how using quantum dots – particles that are a few nanometers in size – will help diagnose a disease. The particles, Sargent explains, shine brightly when exposed to UV light and can be inserted into the body.Theycan also be programmed to bond only to a certain type of cell – a particular cancer cell, for example. Doctors can then use a camera and look for the colored particles, which will help themdeterminewhere cancer cells are growing in a person’s body.

[C] Using this technology, it will be possible to detect cancer at a stage when there are perhaps only a thousand bad cells. Compare this to what happens today: doctors can diagnose cancer only after the dangerous cells have multiplied into the millions and developed into a tumor. One of the advantages of detecting and treating cancer at an early stage is that the cells are less likely to become resistant to drug treatment. In later stages, cancer cells often change and adapt to certain drugs so rapidly that many medicines become ineffective.

Once a certain type of cancer is detected, nanotechnology will also radically improve the way it is treated. Right now, most cancer treatments kill not only the cancerous cells but the healthy ones as well, causing a number of side effects in people. Nanoparticles, on the other hand, will allow doctors to attack cancerous tumors without disturbing healthy cells by delivering cancer-killing drugs to the bad cells only. A second method will be to destroy cancer cells (identified by nanoparticles) using laser rays. Ultimately, technologies like this will allow doctors to deliver cancer treatment earlier, faster, and more thoroughly, with fewer side effects. [D]

Unfortunately, even though nanoparticles have great medical potential, there are serious concerns that these same materials could have negative environmental and health effects. In recent studies, researchers found that half the human cells died after exposing lab-grown human cells to water containing large amounts of nanoparticles.

Because nanotechnology is so potentially useful, many scientists don’t think research into its many uses should be stopped; learning more about nanotechnology should remain a priority. But scientists do believe that governments should allocate more money for safety-related studies – to make sure that large concentrations of nanoparticles do not get into our food and water supplies and cause serious problems.