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Clean Fuel From 'Bionic Leaf' Could Ease Pressure on Farmland A new clean technology to turn sunlight into liquid fuel could shrink the need for large plantations to grow crops for biofuels, Harvard University researchers said on Thursday.That could help protect food supplies and local people's land rights, they suggested.Dubbed "bionic leaf 2.0," the technology uses solar panels to split water molecules into oxygen and hydrogen, the scientists said in a study published in the journal...
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Clean Fuel From 'Bionic Leaf' Could Ease Pressure on Farmland 

A new clean technology to turn sunlight into liquid fuel could shrink the need for large plantations to grow crops for biofuels, Harvard University researchers said on Thursday.

That could help protect food supplies and local people's land rights, they suggested.

Dubbed "bionic leaf 2.0," the technology uses solar panels to split water molecules into oxygen and hydrogen, the scientists said in a study published in the journal Science.

Once separated, hydrogen is moved into a chamber where it is consumed by bacteria, and with help from a special metal catalyst and carbon dioxide, the process generates liquid fuel.

The method is an artificial version of the photosynthesis process plants use to make energy from sunlight, water and carbon dioxide, scientists said.

If it becomes economically viable, the technology could replace oil wells or plantations where food crops are grown for fuel, the study's lead author said.

( Dịch hộ mình )

12
8 tháng 6 2016

Dịch trong google dịch:

     

Một công nghệ sạch mới để biến ánh sáng mặt trời thành nhiên liệu lỏng có thể thu nhỏ nhu cầu cho các đồn điền lớn trồng cây nhiên liệu sinh học, các nhà nghiên cứu trường Đại học Harvard cho biết hôm thứ Năm.

Điều đó có thể giúp bảo vệ nguồn cung cấp thực phẩm và quyền sử dụng đất của người dân, họ đề nghị.

Được mệnh danh là "bionic lá 2.0", công nghệ sử dụng năng lượng mặt trời để tách các phân tử nước thành oxy và hydro, các nhà khoa học cho biết trong một nghiên cứu công bố trên tạp chí Science.

Khi tách ra, hydro được chuyển vào một căn phòng, nơi nó được tiêu thụ bởi các vi khuẩn, và với sự giúp đỡ từ một đặc biệt kim loại xúc tác và carbon dioxide, quá trình tạo ra nhiên liệu lỏng.

Phương pháp này là một phiên bản nhân tạo của quá trình quang hợp thực vật sử dụng để tạo ra năng lượng từ ánh sáng mặt trời, nước và carbon dioxide, các nhà khoa học cho biết.

Nếu nó trở nên hiệu quả kinh tế, công nghệ này có thể thay thế các giếng dầu hoặc các đồn điền nơi cây lương thực được trồng để lấy nhiên liệu, tác giả chính của nghiên cứu cho biết.

Bạn nào dịch được tớ tích cho

The astronauts could not have reached the moon without the invention of rockets. We live in the age of rockets, but do you know that rockets are not a modern (1) _____ ? For centuries, rockets were used to entertain people. The Chinese used rockets (2) ______ fireworks. In the 13th century, rockets were first used in war. The Mongols used rockets to attack a Chinese city in 1232. These early rockets could not (3) ________very far. However, in 1885 a Russian scientist discovered a better...
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The astronauts could not have reached the moon without the invention of rockets. We live in the age of rockets, but do you know that rockets are not a modern

(1) _____ ? For centuries, rockets were used to entertain people. The Chinese used

rockets (2) ______ fireworks. In the 13th century, rockets were first used in war. The

Mongols used rockets to attack a Chinese city in 1232. These early rockets could not

(3) ________very far. However, in 1885 a Russian scientist discovered a better fuel for rockets. This liquid fuel gave rockets much more power. Then in 1919 a new age of rockets began. In that year an American scientist, Robert Goddard, said that it was

(4 )______ to send a rocket to the moon! Goddard launched his first liquid-fuelled rocket

in 1923. It flew 184 feet. Almost 12 years later, he sent a rocket 7,500 feet into the

air in 1935. Russian rockets sent the first (5) ______ into orbit in 1957. Just 12 years

later the first man walked on the moon – thanks to rockets! Where will rockets take us next?

0
24 tháng 2 2018

Rivers are on of the world’s most important natural resources. Many cities are on the large rivers, and ……almost…….. every country has a least one river that …plays…….. an important part in the lives of its people. Besides transportation, river.......provide……………..water for crops, water to drink , and recreation for people who live along their ……banks…….. And in ……order…….to get water for crops, engineers sometimes build a dam…across………a river and let water become a lake behind the dam. Then people can use their water not……only…..to irrigate fields but also to make electricity for homes and industries. ……However…….the water often becomes polluted when cities on river bank grow up and the number of industries increases. We are learning that it is necessary to ……keep……rivers clean if we want to enjoy the benefits of the natural resources.

24 tháng 2 2018

Rivers are on of the world’s most important natural resources. Many cities are on the large rivers, and……almost…….. every country has a least one river that …plays…….. an important part in the lives of its people. Besides transportation, rivers …provide……………..water for crops, water to drink , and recreation for people who live along their ……banks…….. And in ……order…….to get water for crops, engineers sometimes build a dam …across………a river and let water become a lake behind the dam. Then people can use their water not ……only………..to irrigate fields but also to make electricity for homes and industries. ……However…….the water often becomes polluted when cities on river bank grow……in……….size and the number of industries increases. We are learning that it is necessary to……keep……rivers clean if we want to enjoy the benefits of the natural resources.

A rocket uses fuel to make power for the engine. The fuel is set on fire inside the rocket. As the fuel burns, it creates gases that have great pressure. These gases are blasted out of the rocket engines.            These gases all go out the bottom of the rocket engine where it is open. They come out so fast and with so much power that the rocket is pushed up. It is pushed up so hard that the rocket overcomes the force of gravity, which tries to keep everything on the ground. The force that...
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A rocket uses fuel to make power for the engine. The fuel is set on fire inside the rocket. As the fuel burns, it creates gases that have great pressure. These gases are blasted out of the rocket engines.

            These gases all go out the bottom of the rocket engine where it is open. They come out so fast and with so much power that the rocket is pushed up. It is pushed up so hard that the rocket overcomes the force of gravity, which tries to keep everything on the ground. The force that pushes up against the front of the rocket is called thrust.

            Unlike an airplane, a rocket does not use wings to help it fly. It just uses the power and force created by the burning fuel to make enough thrust.

 

 Decide whether the statements are True (T) or False (F).

 

         1. A rocket uses the energy from wind to make power for the engine.             .................

         2. When the fuel burns, it creates gases that have great pressure.                     .................

         3. These gases come so fast but they have little power.                                    .................

         4. The rocket is pushed up because it overcome the force of gravity.              .................

         5. The rocket has two wings which help it fly.                                                  ................. 

1
27 tháng 8 2021

A rocket uses fuel to make power for the engine. The fuel is set on fire inside the rocket. As the fuel burns, it creates gases that have great pressure. These gases are blasted out of the rocket engines.

These gases all go out the bottom of the rocket engine where it is open. They come out so fast and with so much power that the rocket is pushed up. It is pushed up so hard that the rocket overcomes the force of gravity, which tries to keep everything on the ground. The force that pushes up against the front of the rocket is called thrust.

Unlike an airplane, a rocket does not use wings to help it fly. It just uses the power and force created by the burning fuel to make enough thrust.

 Decide whether the statements are True (T) or False (F).

1. A rocket uses the energy from wind to make power for the engine. ...........F......

2. When the fuel burns, it creates gases that have great pressure. ...........T......

3. These gases come so fast but they have little power. .......F..........

4. The rocket is pushed up because it overcome the force of gravity. .......T..........

5. The rocket has two wings which help it fly. ............F..... 

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 37.   In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people...
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Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 37.

  In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people discovered that they could use vegetable oils and animal fats in lieu of gathered or cut wood. Charcoal gave off more intensive heat than wood and was more easily obtainable than organic fats. The Greeks first began to use coal for metal smelting in the 4th century, but it did not come into extensive use until the Industrial Revolution.

  In the 1700s, at the beginning of the Industrial Revolution, most energy used in the United States and other nations undergoing industrialization was obtained from perpetual and renewable sources, such as wood, water streams, domesticated animal labor, and wind. These were predominantly locally available supplies. By mid-1800s, 91 percent of all commercial energy consumed in the United States and European countries was obtained from wood. However, at he beginning of the 20th century, coal became a major energy source and replaced wood in industrializing countries. Although in most regions and climate zones wood was more readily accessible than coal, the latter represents a more concentrated source of energy. In 1910, natural gas and oil firmly replaced coal as the main source of fuel because they are lighter and, therefore, cheaper to transport. They burned more cleanly than coal and polluted less. Unlike coal, oil could be refined to manufacture liquid fuels for vehicles, a very important consideration in the early 1900s, when the automobile arrived on the scene.

  By 1984, non-renewable fossil fuels, such as oil, coal, and natural gas, provided over 82 percent of the commercial and industrial energy used in the world. Small amounts of energy were derived from nuclear fission, and the remaining 16 percent came from burning direct perpetual and renewable fuels, such as biomass. Between 1700 and 1986, a large number of countries shifted from the use of energy from local sources to a centralized generation of hydropower and solar energy converted to electricity. The energy derived from non-renewable fossil fuels has been increasingly produced in one location and transported to another, as is the case with most automobile fuels. In countries with private, rather than public transportation, the age of non-renewable fuels has created a dependency on a finite resource that will have to be replaced.

  Alternative fuel sources are numerous, and shale oil and hydrocarbons are just two examples. The extraction of shale oil from large deposits in Asian and European regions has proven to be labor consuming and costly. The resulting product is sulfur-and nitrogen-rich, and large scale extractions are presently prohibitive. Similarly, the extraction of hydrocarbons from tar sands in Alberta and Utah is complex. Semi-solid hydrocarbons cannot be easily separated from the sandstone and limestone that carry them, and modern technology is not sufficiently versatile for a large-scale removal of the material. However, both sources of fuel may eventually be needed as petroleum prices continue to rise and limitations in fossil fuel availability make alternative deposits more attractive.

According to the passage, what was the greatest advantage of oil as fuel?

A. it was a concentrated source of energy. 

B. it was lighter and cheaper than coal. 

C. it replaced wood and coal and reduced pollution. 

D. it could be converted to automobile fuel.

1
4 tháng 12 2019

Đáp án D

Theo đoạn văn, lợi thế lớn nhất của dầu với vai trò là nhiên liệu là gì?

A. nó là một nguồn năng lượng tập trung.

B. nó là nhẹ hơn và rẻ hơn than.

C. nó thay thế gỗ và than và giảm ô nhiễm.

D. có thể chuyển thành nhiên liệu ô tô.

Dẫn chứng: Unlike coal, oil could be refined to manufacture liquid fuels for vehicles, a very important consideration in the early 1900s, when the automobile arrived on the scene.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 37.   In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people...
Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 37.

  In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people discovered that they could use vegetable oils and animal fats in lieu of gathered or cut wood. Charcoal gave off more intensive heat than wood and was more easily obtainable than organic fats. The Greeks first began to use coal for metal smelting in the 4th century, but it did not come into extensive use until the Industrial Revolution.

  In the 1700s, at the beginning of the Industrial Revolution, most energy used in the United States and other nations undergoing industrialization was obtained from perpetual and renewable sources, such as wood, water streams, domesticated animal labor, and wind. These were predominantly locally available supplies. By mid-1800s, 91 percent of all commercial energy consumed in the United States and European countries was obtained from wood. However, at he beginning of the 20th century, coal became a major energy source and replaced wood in industrializing countries. Although in most regions and climate zones wood was more readily accessible than coal, the latter represents a more concentrated source of energy. In 1910, natural gas and oil firmly replaced coal as the main source of fuel because they are lighter and, therefore, cheaper to transport. They burned more cleanly than coal and polluted less. Unlike coal, oil could be refined to manufacture liquid fuels for vehicles, a very important consideration in the early 1900s, when the automobile arrived on the scene.

  By 1984, non-renewable fossil fuels, such as oil, coal, and natural gas, provided over 82 percent of the commercial and industrial energy used in the world. Small amounts of energy were derived from nuclear fission, and the remaining 16 percent came from burning direct perpetual and renewable fuels, such as biomass. Between 1700 and 1986, a large number of countries shifted from the use of energy from local sources to a centralized generation of hydropower and solar energy converted to electricity. The energy derived from non-renewable fossil fuels has been increasingly produced in one location and transported to another, as is the case with most automobile fuels. In countries with private, rather than public transportation, the age of non-renewable fuels has created a dependency on a finite resource that will have to be replaced.

  Alternative fuel sources are numerous, and shale oil and hydrocarbons are just two examples. The extraction of shale oil from large deposits in Asian and European regions has proven to be labor consuming and costly. The resulting product is sulfur-and nitrogen-rich, and large scale extractions are presently prohibitive. Similarly, the extraction of hydrocarbons from tar sands in Alberta and Utah is complex. Semi-solid hydrocarbons cannot be easily separated from the sandstone and limestone that carry them, and modern technology is not sufficiently versatile for a large-scale removal of the material. However, both sources of fuel may eventually be needed as petroleum prices continue to rise and limitations in fossil fuel availability make alternative deposits more attractive.

The author of the passage implies that alternative sources of fuel are curently

A. being used for consumption

B. available in few locations 

C. being explored

D. examined on a large scale

1
21 tháng 5 2018

Đáp án A

Tác giả của đoạn văn ngụ ý rằng các nguồn thay thế nhiên liệu gần đây 

A. được sử dụng để tiêu thụ

B. có sẵn ở vài địa điểm

C. được khám phá

D. kiểm tra ở quy mô lớn

Dẫn chứng: The extraction of shale oil from large deposits in Asian and European regions has proven to be labor consuming and costly.

Read the following passage and write the letter A, B, C or D on the top of the first page to indicate the correct answer to each of the questions.In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people discovered...
Đọc tiếp

Read the following passage and write the letter A, B, C or D on the top of the first page to indicate the correct answer to each of the questions.

In the course of its history, human inventions have dramatically increased the average amount of energy available for use per person. Primitive peoples in cold regions burned wood and animal dung to heat their caves, cook food, and drive off animals by fire. The first step toward the developing of more efficient fuels was taken when people discovered that they could use vegetable oils and animal fats in lieu of gathered or cut wood. Charcoal gave off more intensive heat than wood and was more easily obtainable than organic fats. The Greeks first began to use coal for metal smelting in the 4th century, but it did not come into extensive use until the Industrial Revolution.

In the 1700s, at the beginning of the Industrial Revolution, most energy used in the United States and other nations undergoing industrialization was obtained from perpetual and renewable sources, such as wood, water streams, domesticated animal labor, and wind. These were predominantly locally available supplies. By mid-1800s, 91 percent of all commercial energy consumed in the United States and European countries was obtained from wood. However, at he beginning of the 20th century, coal became a major energy source and replaced wood in industrializing countries. Although in most regions and climate zones wood was more readily accessible than coal, the latter represents a more concentrated source of energy. In 1910, natural gas and oil firmly replaced coal as the main source of fuel because they are lighter and, therefore, cheaper to transport. They burned more cleanly than coal and polluted less. Unlike coal, oil could be refined to manufacture liquid fuels for vehicles, a very important consideration in the early 1900s, when the automobile arrived on the scene.

By 1984, non-renewable fossil fuels, such as oil, coal, and natural gas, provided over 82 percent of the commercial and industrial energy used in the world. Small amounts of energy were derived from nuclear fission, and the remaining 16 percent came from burning direct perpetual and renewable fuels, such as biomass. Between 1700 and 1986, a large number of countries shifted from the use of energy from local sources to a centralized generation of hydropower and solar energy converted to electricity. The energy derived from non-renewable fossil fuels has been increasingly produced in one location and transported to another, as is the case with most automobile fuels. In countries with private, rather than public transportation, the age of non-renewable fuels has created a dependency on a finite resource that will have to be replaced.

Alternative fuel sources are numerous, and shale oil and hydrocarbons are just two examples. The extraction of shale oil from large deposits in Asian and European regions has proven to be labor consuming and costly. The resulting product is sulfur-and nitrogen-rich, and large scale extractions are presently prohibitive. Similarly, the extraction of hydrocarbons from tar sands in Alberta and Utah is complex. Semi-solid hydrocarbons cannot be easily separated from the sandstone and limestone that carry them, and modern technology is not sufficiently versatile for a large-scale removal of the material. However, both sources of fuel may eventually be needed as petroleum prices continue to rise and limitations in fossil fuel availability make alternative deposits more attractive.
Question:
According to the passage, what was the greatest advantage of oil as fuel?

A. it was a concentrated source of energy.

B. it was lighter and cheaper than coal.

C. it replaced wood and coal and reduced pollution.

D. it could be converted to automobile fuel.

1
24 tháng 7 2018

Đáp án D

Kiến thức: Đọc hiểu 

Giải thích:

Theo đoạn văn, lợi thế lớn nhất của dầu với vai trò là nhiên liệu là gì?

A. nó là một nguồn năng lượng tập trung.     B. nó là nhẹ hơn và rẻ hơn than.

C. nó thay thế gỗ và than và giảm ô nhiễm.   D. có thể chuyển thành nhiên liệu ô tô.

Dẫn chứng: Unlike coal, oil could be refined to manufacture liquid fuels for vehicles, a very important consideration in the early 1900s, when the automobile arrived on the scene.

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.         Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity....
Đọc tiếp

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.

        Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity. However, nuclear fission forms dangerous radioactive waste.

          Sunlight offers many ways to get energy. A window can allow warm sunlight into your room. Solar water-heating systems can use sunlight to warm the water for your home, swimming pool and school. Sunlight also warms the Earth and causes wind. Electricity can be made by wind generators.

Photovoltaic, or PV system use a type of material that converts sunlight into electricity. PV systems can power your air conditioner or a satellite like the International Space Station. PV systems are also used to run a calculator, recharge cell phone, or even power lightweight cars.

          Sunlight is also changed into electricity by concentrating solar power or CSP systems. CSP systems have mirrors that focus the sunlight. The concentrated sunlight turns water into steam which turns a turbine that is connected to an electric generator. A CSP system usually uses sunlight to make steam. CSP power plants can store large amount of heat. The stored heat is used to make electricity at night. During cloud days, many CSP plants can also burn natural gas to provide the heat that is used to turn water into steam.

         Sunlight provides the energy needed to grow plants and make large amount of environmentally friendly heat and electricity. Solar energy can provide power today and for a long time in the future.

To help the readers understand some of the benefits of solar energy, the author ________

A. provides a list of solar energy projects.

B. lists in chronological order the invention of various systems that gather the energy of sunlight

C. describes in detail how a PV system works.

D. briefly compares and contrasts the differences in using fossil fuels, nuclear fission and solar energy in electric power systems

1
28 tháng 9 2018

Đáp án D

Để giúp độc giả hiểu về ích lợi của năng lượng mặt trời, tác giả ______

A. liệt kê một loạt dự án quang năng.

B. liệt kê theo thứ tự ra đời của các hệ thống tập hợp năng lượng mặt trời.

C. mô tả chi tiết quy trình của hệ thống PV.

D. so sánh ngắn gọn và tương phản sự khác biệt trong việc dùng nhiên liệu hoá thạch, hạt nhân nguyên tử và năng lượng mặt trời trong hệ thống điện năng.

Trong đoạn 1, tác giả đưa ra sự so sánh và tương phản ngắn gọn về các dang năng lượng, nêu lên tác dụng và hạn chế của chúng, từ đó làm bật lên lợi ích của năng lượng mặt trờ

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.         Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity....
Đọc tiếp

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.

        Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity. However, nuclear fission forms dangerous radioactive waste.

          Sunlight offers many ways to get energy. A window can allow warm sunlight into your room. Solar water-heating systems can use sunlight to warm the water for your home, swimming pool and school. Sunlight also warms the Earth and causes wind. Electricity can be made by wind generators.

Photovoltaic, or PV system use a type of material that converts sunlight into electricity. PV systems can power your air conditioner or a satellite like the International Space Station. PV systems are also used to run a calculator, recharge cell phone, or even power lightweight cars.

          Sunlight is also changed into electricity by concentrating solar power or CSP systems. CSP systems have mirrors that focus the sunlight. The concentrated sunlight turns water into steam which turns a turbine that is connected to an electric generator. A CSP system usually uses sunlight to make steam. CSP power plants can store large amount of heat. The stored heat is used to make electricity at night. During cloud days, many CSP plants can also burn natural gas to provide the heat that is used to turn water into steam.

         Sunlight provides the energy needed to grow plants and make large amount of environmentally friendly heat and electricity. Solar energy can provide power today and for a long time in the future.

In the third paragraph, the word “convert” is closest in meaning to _______

A. change form one religion to another 

B. transform

C. exchange for something equal in value

D. converse

1
19 tháng 8 2018

Đáp án B

Trong đoạn 3, từ “convert” gần nghĩa nhất với________

A. thay đổi hình thức một tôn giáo

B. thay đổi, cải biến

C. đổi sang thứ gì đó có giá trị tương đương

D. nói chuyện (to) convert = (to) transform: thay đổi, biến đổi

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.         Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity....
Đọc tiếp

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.

        Sunlight is solar energy. Sunlight is needed for growing plants that you eat to get energy. Sunlight is also used to make clean electricity. Burning fossil fuels to make electricity pollutes our atmosphere and rivers. Fossil fuels are expensive and limited sources of energy. Nuclear fission is used to create enormous amount of heat and electricity. However, nuclear fission forms dangerous radioactive waste.

          Sunlight offers many ways to get energy. A window can allow warm sunlight into your room. Solar water-heating systems can use sunlight to warm the water for your home, swimming pool and school. Sunlight also warms the Earth and causes wind. Electricity can be made by wind generators.

Photovoltaic, or PV system use a type of material that converts sunlight into electricity. PV systems can power your air conditioner or a satellite like the International Space Station. PV systems are also used to run a calculator, recharge cell phone, or even power lightweight cars.

          Sunlight is also changed into electricity by concentrating solar power or CSP systems. CSP systems have mirrors that focus the sunlight. The concentrated sunlight turns water into steam which turns a turbine that is connected to an electric generator. A CSP system usually uses sunlight to make steam. CSP power plants can store large amount of heat. The stored heat is used to make electricity at night. During cloud days, many CSP plants can also burn natural gas to provide the heat that is used to turn water into steam.

         Sunlight provides the energy needed to grow plants and make large amount of environmentally friendly heat and electricity. Solar energy can provide power today and for a long time in the future.

In the fourth paragraph, the word “which” refers to _______

A. water               

B. steam                

C. sunlight            

D. solar power

1
5 tháng 8 2017

Đáp án B

Trong đoạn 4, từ “which” nói đến ________

A. nước

B. hơi nước

C. ánh sáng mặt trời

D. năng lượng mặt trời

“The concentrated sunlight turns water into steam which turns a turbine that is connected to an electric generator.”

(Ánh sáng được tập trung chuyển nước từ dạng lỏng sang dạng hơi – làm xoay tuabin được nối với máy phát điện.)

Thứ làm xoay tuabin chính là hơi nước – steam.