单选题We learn from the passage that ______.A all living things on the earth depend on the sun for their foodB a forest looks dark in winter because it absorbs solar energyC only 0.023 of the energy from the sun is made use of on the earthD greenhouse gases
题目
单选题
We learn from the passage that ______.
A
all living things on the earth depend on the sun for their food
B
a forest looks dark in winter because it absorbs solar energy
C
only 0.023 of the energy from the sun is made use of on the earth
D
greenhouse gases allow heat energy to escape from the earth’ s surface
相似考题
参考答案和解析
正确答案：
A
解析：
根据第一段Sunlight also provides the energy used by green plants to make their own food，阳光给绿色植物提供能量使其生产自己的食物，故选A。
根据第一段Sunlight also provides the energy used by green plants to make their own food，阳光给绿色植物提供能量使其生产自己的食物，故选A。
更多“单选题We learn from the passage that ______.A all living things on the earth depend on the sun for their foodB a forest looks dark in winter because it absorbs solar energyC only 0.023 of the energy from the sun is made use of on the earthD greenhouse gases ”相关问题
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第1题：
24． The passage tells us __________．
A． the sun is not the biggest star
B． the sun is bigger than any other star
C． only the sun can shine
D． the sun is one of the farthest stars from us
正确答案：A
24.A【解析】由第四段中“There are many big stars we can-t see... because it is the nearest of all sta rs．”可知。 -
第2题：
For what purpose are the diving pipes used?
A. To absorb heat from the sun.
B. To store heat for future use.
C. To turn solar energy into heat energy.
D. To carry heat down below the surface.
正确答案：D
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第3题：
To get some idea of the amount of heat the sun ________(1), think about this. If you ________(2)collect all the heat that hits the earth in a two-week period, it would equal the amount of all the other known sources and reserves of energy: wood, coal, and oil. But even these sources of energy depend ________(3) the sun for their formation. For example, a tree ________ (4) certainly never grow and provide fuel in the form. of wood were it not for the sun. Because the sun is so important in the production of all forms of heating fuel, more and more time and money are being spent ________(5) ways to change power from the sun directly into a form. of heat.
1.
A、gives off
B、turns off
C、takes off
D、sets off
2.
A、will
B、could
C、must
D、shall
3.
A、of
B、in
C、on
D、to
4.
A、will
B、must
C、shall
D、would
5.
A、study
B、studied
C、studying
D、being studying
参考答案：ABCDC
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第4题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Infrared radiation can produce heat______.
A:when it is absorbed by matter
B:when it is cloudy
C:because they can pass through solid objects
D:when the sunrays are fierce.
E:when a change in the nucleus of an atom takes place
F:when electron rearrangement takes place答案：A解析：通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
根据第五段第五句可知，化学能是在电子重组时产生的。 -
第5题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.X-rays and gamma rays can be used to detect and treat cancer______.
A:when it is absorbed by matter
B:when it is cloudy
C:because they can pass through solid objects
D:when the sunrays are fierce.
E:when a change in the nucleus of an atom takes place
F:when electron rearrangement takes place答案：C解析：通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
根据第五段第五句可知，化学能是在电子重组时产生的。 -
第6题：
共用题干
第一篇
The Northern Lights
The sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.
The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.
Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.
Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.
We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!The solar wind comes into being as a result of_______.
A:disappearance of the Sun's gravity
B:unpredictable weather of the Sun
C:fast flow of energy away from the Sun
D:a stream of particles being blown away答案：C解析：本篇文章主要介绍了北极光的形成、运动以及色彩。
根据第一段第三、四句可知，热量在时速约100万英里的带电粒子流中由太阳向地球流动，这些粒子被称为等离子体，源于太阳的等离子体流又被称为太阳风。由此不难推测出，太阳风是能量从太阳向地球高速流动造成的，所以选择C项。
根据第二段第三句可知，带电粒子被困在环绕地球的磁场中，并且根据第一段第三、四句以及第二段第一句可知，这些带电粒子即为太阳风。由此可知，太阳风吹向地球时，会被地球外围的磁场束缚住，所以选择A项。
根据第二段最后一句可知，电子落向地球时与大气中的气体分子碰撞而产生了光芒；根据第三段第一句和第三句可知，碰撞后每种大气分子发出的光芒不同；不同的光芒在天空中闪现，造成了北极光和南极光；根据第二段第五句可知，原子粒子被称为电子。由此推出，北极光是由电子，即原子粒子，与大气中的气体分子碰撞造成的。
根据第四段第二句可知，北极光穿过天空的速度通常足够慢，能够让人看到，但是它们可能也会跳动、闪烁，甚至会像波浪一样。由此可知，北极光移动的速度很慢，能够被人用眼观察，所以选择A项。
最后一段表明，作者希望望人在一生中至少应该去看一次北极光，并且说他知道我们会感到难忘。可见作者对北极光是喜爱的，所以选择D项。 -
第7题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.We can use energy from the sun because_______________.
A:electromagnetic energy
B:electromagnetic energy travels through space
C:came from the sun
D:when a change in the nucleus of an atom takes place
E:whlen the sunrays are fierce
F:chemical energy is generated答案：B解析：第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。 -
第8题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.Paragraph 4__________________
A:Nuclear Reactions as the Lasting Source of the Sun's Energy
B:The Most Imoprtant Source of Energy
C:Types of Eleetromagnetie Energy
D:X-rays Are Used to Detect and Treat Cancer
E:Seeking New Sourees of Energy
F:Nuclear Energy Is Beginning to Compete With Coal答案：B解析：第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。 -
第9题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.When electron rearrangement takes place_______________.
A:electromagnetic energy
B:electromagnetic energy travels through space
C:came from the sun
D:when a change in the nucleus of an atom takes place
E:whlen the sunrays are fierce
F:chemical energy is generated答案：F解析：第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。 -
第10题：
共用题干
Weight on and off the Earth We are so used to.our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted.Because we can feel that things are heavy,we think of "weight"as being a fixed quality in an object,but it is not really fixed at all.If you could take a one-pound packet of butter 4,000 miles out from the earth,it would weigh only a quarter of a pound. Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space?The reason is this:all objects have a natural attraction for all other objects;this is called gravitational attraction.But this power of attraction between two obects gets weaker as they get farther apart.When the butter was at the surface of the earth,it was 4,000 miles from the center.When we took the butter 4,000 miles out,it was 8,000 miles from the center,which is twice the distance.If you double the distance between two objects,their gravitational attraction decreases two times two.If you treble the distance, it gets nine times weaker(three times three)and so on. So this is one of the first things we need to remember that the weight of an object in space is not the same as its weight on the surface of the earth. What about the weight of our pound of butter on the surface of the moon?At the distance the puii of the earth is about 4,000 times smaller than it is here on the surface,so we can forget all about the earth-pull on our butter. On the other hand,on the moon there will be an attraction between the butter and the moon,but the butter will weigh only about one-sixth as much as it does on the earth.This is because the moon is so much smaller than the earth.The amount of gravitational pull that a body produces depends on the amount of material in it.A packet of butter has a gravitational pull of its own;but this is very small in relation to the pull of something as large as the moon,or the earth,or the sun.The main idea of this passage is
A:different weight systems in different places
B:freedom from traditional ideas
C:traveling from the earth to the moon
D:the effect of gravitation on weight答案：D解析：第一段最后一句表明，1磅重的黄油在离地球表面4000英里处重达0.25磅，第二段第一句也表明在4000英里高空处的物体重量仅为其在地球表面的重量的1/4。由此可推算出，4磅重的茶叶在离地球表面4000英里处重达1磅。
第一段第一句表明，我们之所以不能打破固有思维，是因为我们已经习惯了地球上的生活，也就是说，我们正是因为太过熟悉地球上的事物，才没有去质疑这些固有思维。
第一段第二句表明，物体的重量并非固定不变。第二段解释说，物体的重量源于物体间的引力。也就是说，物体的重量随着物体间引力的改变而改变。
最后一段第三句说明一个物体产生的引力与物体本身的重量有关。最后一段第四句又表明由于本身重量较小，一包黄油产生的引力很有限，相对于月球、地球、太阳等产生的强劲引力来说，比较容易被我们忽略。
本篇文章通篇讲的是重量是由引力产生的，并进一步阐述了物体间引力的变化、物体本身的重量，以及物体间的距离这三者之间的关系，主要讲的还是引力对重量的作用。 -
第11题：
The sun heats the earth,（）is very important to living things.
- A、that
- B、what
- C、which
正确答案:C -
第12题：
单选题Only a small part of the sun’s energy reaches the earth’ s surface because most of it is ______.Aabsorbed by the clouds in the lower atmosphere
Breflected by the gases in the upper atmosphere
Clost in the upper and lower atmosphere
Dused to evaporate water from the oceans and lakes
正确答案： B解析：
根据第二段It is either reflected or absorbed by the gases in the upper atmosphere. Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or the earth’s surface.太阳的多数能量是被高空中的大气反射或者吸收。因此B选项正确。 -
第13题：
25． Why do we call the sun"a life-giving star"?
A． Because it gives us warmth．
B． Because there are some living things on it．
C． Because plants and animals can't live without it．
D． Because people have to live in the dark without it．
正确答案：C
z5.C【解析】由最后一段中“The' sun gives us...1t makes life possible on our earth.”可知。 -
第14题：
A greenhouse is a building made of glass which is used for keeping plants when the outside temperature is low. In a similar way there are several gases in the atmosphere which trap(捕捉)the heat produced by the sun and prevent it from escaping. These gases are known as"greenhouse gases"，and the way in which they trap heat in the atmosphere is called the "greenhouse effect". This is not simply air pollution. Most of the main greenhouse gases exist naturally in small amounts in our atmosphere, and without them earth would be 30 degrees colder and human life would not exist. In other words, the greenhouse effect is a natural course which is to some degree helpful to us.
The problem is that in the last century and a half, we have been putting too many of these gases into the earth's atmosphere by burning large quantities of coal and oil and by cutting down forests. The rapid increase in greenhouse gases is making the world warmer. The world's temperature has already gone up by half a degree this century, and the sea level has risen by 10 centimetres. If the amount of carbon dioxide(二氧化碳)in the atmosphere doubles, there will probably be a rise in the earth's temperature of between 1 and 4 degrees. This may seem a small increase, but it would be enough to cause major changes in geography and agriculture. Large areas of the world would be flooded, and some areas would become dry and unable to produce crops. It is important, too, to consider that there may be a delay of about 30 years in the greenhouse effect. This means that we are probably experiencing only now the effect of the gases put into the atmosphere before the 1960s. Since then, our use of these gases has greatly increased.
1. The"greenhouse effect"means _____.
A. the way in which gases are used for keeping plants warm
B. a natural course which is some degree helpful to us
C. the way"greenhouse gases"trap heat on the earth
D. the whole course in which greenhouse gases prevent heat
2. If there were no greenhouse effect, _____.
A. no plants would grow on our planet
B. earth would be thirty degrees colder
C. man could not live on the earth
D. All of the above answers are correct
3. Which of the following is NOT true? _____
A. Burning too much coal and oil produces lots of greenhouse gases.
B. It has become warmer on the earth now than in the past.
C. Gases put into the atmosphere now will affect the earth years later.
D. The temperature in a greenhouse is as high as that in the atmosphere.
4. Suppose the earth's temperature rose by 3 degrees, _____.
A. great harm would be done to mankind
B. the sea level would go by 10 centimetres
C. all the land in the world would be flooded
D. crops would be unable to grow on the earth
5. This passage mainly deals with _____.
A. the concept(概念)and harm of greenhouse effect
B. the relation between greenhouse gases and man
C. the concept and change of greenhouse effect
D. the effect of the rise of the earth's temperature
参考答案： BDDAC
-
第15题：
Neap tides occur ______.
A.at the start of spring, when the Sun is nearly over the equator
B.only when the Sun and Moon are on the same sides of the Earth and are nearly in line
C.when the Sun and Moon are at approximately 90°to each other, as seen from the Earth
D.when the Sun , Moon, and Earth are nearly in line, regardless of alignment order
正确答案：C
小潮发生在当从地球看太阳和月亮与地球接近90度时。 -
第16题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Paragraph 4______
A:Nuclear Reactions as the Lasting Source of the Sun's Energy
B:The Most Important Source of Energy
C:Types of Electromagnetic Energy
D:The Machines Used for Energy Generation
E:Seeking New Sources of Energy
F:The Use of Ultravio1et Radiation in Medicine答案：B解析：通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
根据第五段第五句可知，化学能是在电子重组时产生的。 -
第17题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Chemical energy is generated______.
A:when it is absorbed by matter
B:when it is cloudy
C:because they can pass through solid objects
D:when the sunrays are fierce.
E:when a change in the nucleus of an atom takes place
F:when electron rearrangement takes place答案：F解析：通读文章可知，第三段第一句是段落主题句，紧接着围绕第一句进行了具体阐述，根据第一句中出现的“types of electromagnetic energy”可知，第三段主要讲述几种不同种类的电磁能，应选择C项。
根据第四段第一、二句可知，我们通常用电来生成电磁能，使用的很多能源都来自太阳。紧接着又表明，水能源于来自太阳的热能，煤储存的能量也是来自太阳。因此不难得出，第四段讲的是能量最重要的来源，即太阳。
第五段开头提到太阳能的来源仍是个谜，随后对此进行了分析，最后得出太阳能来自核反应释放的能量。由此可知，第五段主要讲的是，氢原子转变为氦原子的核反应释放的能量是太阳能的来源。几个选项中只有A项提到核反应是太阳能的持久来源，因此选择A项。
通读文章可知，第六段的最后一句是主题句。这句话的大意是：科学家正继续在寻找更好的新方法来获取并使用能源。几个选项中只有E项与之契合，因此选择E项。
根据第一段第四句可知，你即便在感到凉爽的阴天，也有可能被阳光灼伤，因此选择B项。
根据第三段第三、四句可知，红外线是电磁波，当它被物质吸收时，会产生能量。
根据第三段倒数第二、三句可知，X射线和伽马射线之所以能用来探测和治疗癌症，是因为具有很多能量的x射线和伽马射线能穿透固体。
根据第五段第五句可知，化学能是在电子重组时产生的。 -
第18题：
共用题干
California Gives Green Light to Space Solar Power
Energy beamed down from space is one step closer to reality,now that California has given the green
light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts（兆瓦）of power
beamed down from solar-power satellites beginning in 2016.But some major challenges will have to be
overcome if the technology is to be used widely.
A start-up company called Solaren is designing the satellites,which it says will use radio waves to beam
energy down to a receiving station on Earth.
The attraction of collecting solar power in space is the almost uninterrupted sunshine available in geo-
synchronous（与地球同步的）orbit. Earth-based solar cells , by contrast , can only collect sun light during day-
time and when skies are clear.
But space-based solar power must grapple（努力克服）with the high cost per kilogram of launching things in-
to space,says Richard Schwartz of Purdue University in West Lafayette,Indiana."if you're talking about it being
economically viable for power of the Earth,it's a tough go,"he says.
Cal Boerman,Solaren's director of energy services,says the company designed its satellites with a view
to keeping launch costs down."We knew we had to come up with a different,revolutionary design,"he says.
A patent the company has won describes ways to reduce the system's weight,including using inflatable mir-
rors to focus sunlight on solar cells,so a smaller number can collect the same amount of energy.
But using mirrors introduces other challenges,including keeping the solar cells from overheating,says
Schwartz."You have to take care of heat dissipation（散发）because you're now concentrating a lot of energy
in one place,"he says.According to the company's patent,Solaren's solar cells will be connected to radia-
tors to help keep them cool.
Though Boerman says the company believes it can make space-based solar power work,it is not expec-
ting to crowd out other forms of renewable energy.Laws in California and other states require increasing use
of renewable energy in coming years,he points out."To meet those needs,we're going to need all types of
renewable energy sources,"he says.Solar-power satellites will use radio waves to beam energy down from space.
A:Right
B:Wrong
C:Not mentioned答案：A解析：根据短文第二段可知，太阳能卫星会使用无线电波将能源发送到地球上的接收站。
短文在第一段中讲太平洋天然气和电力公司将购买200兆瓦的从太阳能电站的卫星上 发送来的电力时提到了200这个数字。
短文在第三段末尾提到：地球上的太阳能电池只能在白天且无云的时候收集阳光。
根据短文第四段可知，在太空的太阳能工厂必须努力克服的问题是：向太空每发射一 千克的物品都要付出高昂代价，即成本高的问题。
根据短文第五段的最后一句可知答案。
根据短文最后一段可知，从太空中获得的太阳能并不会挤掉其他形式的可再生能源。
短文主要围绕美国，尤其是加州来说，并没有提到其他国家的情况。 -
第19题：
共用题干
Weight on and off the Earth We are so used to.our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted.Because we can feel that things are heavy,we think of "weight"as being a fixed quality in an object,but it is not really fixed at all.If you could take a one-pound packet of butter 4,000 miles out from the earth,it would weigh only a quarter of a pound. Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space?The reason is this:all objects have a natural attraction for all other objects;this is called gravitational attraction.But this power of attraction between two obects gets weaker as they get farther apart.When the butter was at the surface of the earth,it was 4,000 miles from the center.When we took the butter 4,000 miles out,it was 8,000 miles from the center,which is twice the distance.If you double the distance between two objects,their gravitational attraction decreases two times two.If you treble the distance, it gets nine times weaker(three times three)and so on. So this is one of the first things we need to remember that the weight of an object in space is not the same as its weight on the surface of the earth. What about the weight of our pound of butter on the surface of the moon?At the distance the puii of the earth is about 4,000 times smaller than it is here on the surface,so we can forget all about the earth-pull on our butter. On the other hand,on the moon there will be an attraction between the butter and the moon,but the butter will weigh only about one-sixth as much as it does on the earth.This is because the moon is so much smaller than the earth.The amount of gravitational pull that a body produces depends on the amount of material in it.A packet of butter has a gravitational pull of its own;but this is very small in relation to the pull of something as large as the moon,or the earth,or the sun.According to the passage,"weight"should be understood in the sense that
A:it is fixed if it is outside the earth's gravitational puli
B:it decreases four times when it is 4,000 miles from the earth's center
C:it varies with the change of the gravitational attraction between two objects
D:things increase in amount as they are closer to the earth's surface答案：C解析：第一段最后一句表明，1磅重的黄油在离地球表面4000英里处重达0.25磅，第二段第一句也表明在4000英里高空处的物体重量仅为其在地球表面的重量的1/4。由此可推算出，4磅重的茶叶在离地球表面4000英里处重达1磅。
第一段第一句表明，我们之所以不能打破固有思维，是因为我们已经习惯了地球上的生活，也就是说，我们正是因为太过熟悉地球上的事物，才没有去质疑这些固有思维。
第一段第二句表明，物体的重量并非固定不变。第二段解释说，物体的重量源于物体间的引力。也就是说，物体的重量随着物体间引力的改变而改变。
最后一段第三句说明一个物体产生的引力与物体本身的重量有关。最后一段第四句又表明由于本身重量较小，一包黄油产生的引力很有限，相对于月球、地球、太阳等产生的强劲引力来说，比较容易被我们忽略。
本篇文章通篇讲的是重量是由引力产生的，并进一步阐述了物体间引力的变化、物体本身的重量，以及物体间的距离这三者之间的关系，主要讲的还是引力对重量的作用。 -
第20题：
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.The energy stored in coal_______________.
A:electromagnetic energy
B:electromagnetic energy travels through space
C:came from the sun
D:when a change in the nucleus of an atom takes place
E:whlen the sunrays are fierce
F:chemical energy is generated答案：C解析：第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。 -
第21题：
共用题干
Weight on and off the Earth We are so used to.our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted.Because we can feel that things are heavy,we think of "weight"as being a fixed quality in an object,but it is not really fixed at all.If you could take a one-pound packet of butter 4,000 miles out from the earth,it would weigh only a quarter of a pound. Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space?The reason is this:all objects have a natural attraction for all other objects;this is called gravitational attraction.But this power of attraction between two obects gets weaker as they get farther apart.When the butter was at the surface of the earth,it was 4,000 miles from the center.When we took the butter 4,000 miles out,it was 8,000 miles from the center,which is twice the distance.If you double the distance between two objects,their gravitational attraction decreases two times two.If you treble the distance, it gets nine times weaker(three times three)and so on. So this is one of the first things we need to remember that the weight of an object in space is not the same as its weight on the surface of the earth. What about the weight of our pound of butter on the surface of the moon?At the distance the puii of the earth is about 4,000 times smaller than it is here on the surface,so we can forget all about the earth-pull on our butter. On the other hand,on the moon there will be an attraction between the butter and the moon,but the butter will weigh only about one-sixth as much as it does on the earth.This is because the moon is so much smaller than the earth.The amount of gravitational pull that a body produces depends on the amount of material in it.A packet of butter has a gravitational pull of its own;but this is very small in relation to the pull of something as large as the moon,or the earth,or the sun.We find it hard to break free from ideas connected with living on the earth because______.
A:it demands too great an effort for us to do so
B:we are too familiar with the way things are to question the ideas
C:we have proved that those ideas are correct
D:we are so sure of ourselves that we never doubt anything on the earth答案：B解析：第一段最后一句表明，1磅重的黄油在离地球表面4000英里处重达0.25磅，第二段第一句也表明在4000英里高空处的物体重量仅为其在地球表面的重量的1/4。由此可推算出，4磅重的茶叶在离地球表面4000英里处重达1磅。
第一段第一句表明，我们之所以不能打破固有思维，是因为我们已经习惯了地球上的生活，也就是说，我们正是因为太过熟悉地球上的事物，才没有去质疑这些固有思维。
第一段第二句表明，物体的重量并非固定不变。第二段解释说，物体的重量源于物体间的引力。也就是说，物体的重量随着物体间引力的改变而改变。
最后一段第三句说明一个物体产生的引力与物体本身的重量有关。最后一段第四句又表明由于本身重量较小，一包黄油产生的引力很有限，相对于月球、地球、太阳等产生的强劲引力来说，比较容易被我们忽略。
本篇文章通篇讲的是重量是由引力产生的，并进一步阐述了物体间引力的变化、物体本身的重量，以及物体间的距离这三者之间的关系，主要讲的还是引力对重量的作用。 -
第22题：
The sun heats the earth,（）is very important to living things.
Athat
Bwhat
Cwhich
Dwhere
C
略 -
第23题：
单选题The sun heats the earth,（）is very important to living things.Athat
Bwhat
Cwhich
正确答案： C解析： 暂无解析