He ______ prison two years ago and now he _______.　　

　 A. was put in; was set free 　    B. was shut into, is set free

　 C. put into, has been set freely 　 D. was put into; has been set free

He ______ prison two years ago and now he _______.

　 A. was put in; was set free 　      B. was shut into, is set free

　 C. put into, has been set freely 　 D. was put into; has been set free

He ______ prison two years ago and now he _______.

　 A. was put in; was set free 　 B. was shut into, is set free

　 C. put into, has been set freely 　 D. was put into; has been set free

The making of glass is a very old industry—at least 4 500 years old. Glass has many extraordinary qualities and it is frequently being used in new ways. One of the most interesting new uses for glass is in telephone communication. Scientists have developed glass fibers as thin as human hair which are designed to carry light signals. When the light reaches the other end, it is first changed into electrical signals, which are in turn converted(转变) into sound messages. Called light wave communication， the new system was used successfully in an experiment in Chicago in 1977. During the experiment two glass fibers were able to carry 672 conversations at the same time. The light wave cable, containing 144 glass fibers, has the capacity(容量) to carry 50 000 conversations at the same time. The light wave communication system has two important advantages. First the glass fiber cables are smaller and weigh less than copper(铜) cables; second, they cost less.

1. One of the extraordinary qualities of glass is that it can carry_______.

A. any signal    　　　　　　　　　　　　　　　　　　  B. light signals

C. sound signals    　　　　　　　　　　　　　　　　 D. electrical signals

2. Before you can hear a message on the telephone using the new system_______.

A. the light signals have to be changed into electrical sound

B. neither the light nor the electrical signals have to be changed in any way

C. light must first be changed into electrical signals and then into sound

D. electrical signals must first be changed into light signals and then into sound

3. According to the passage the new telephone communication system_______.

A. was put on experiment in 1977

B. had been put into actual use by 1977

C. had been repeatedly experimented before 1977

D. was first put into actual use in 1977

4. From the passage, you can tell that people prefer glass fiber cables to copper cables because_______.

A. glass fiber is easier to make

B. glass fiber is less expensive

C. glass fiber is more up to date

D. glass fiber delivers messages directly

5. Which of the following statements best expresses the main idea of the passage?

A. Light signals have changed the use of glass in industry.

B. Glass fibers have reduced the cost of telephone communication.

C. Glass is very useful because it has many unusual qualities.

D. The use of glass fibers to carry telephone messages is an interesting new development.

In the past, man did not have to think about the protection of his environment(环境). There were few people on the earth, and natural resources seemed to be 　　1    .

Today things are 　　2    . The world has become too 　　3    . We are using up our natural resources too quickly, and at the same time we are 　　4     our environment with dangerous chemicals. If we 　　5     to do this, human life on the earth will not survive(幸存).

Everyone 　　6     today that if too many fishes are taken from the sea, there will soon be none left. Yet with modern fishing 　　7    , more and more fishes are caught. We know that if too many trees are cut down, 　　8    will disappear and nothing will grow on the land. Yet, we 　　9    to use bigger and more powerful machines to 　　10     more and more trees. We realize that if rivers are polluted with waste products from factories, we will die. 　　11   , in most countries, waste products are 　　12     put into rivers or into the sea, and there are 　　13     laws to stop this.

We know, too, that if the 　　14     of the world continues to rise at the present rate, in a few years, there will not be enough 　　15    . What can we do to solve(解决) these problems?

If we eat more vegetables and less    16   , there will be more food available(可得到的) for everyone. Land that is used to grow crops 　　17     five times more people than land where animals are kept.

Our natural resources will 　　18     longer if we learn to recycle them.

The world population will not rise so quickly if people use modern methods of birth   19    .

Finally, if we educate people to think about the problems, we shall have a better and cleaner 　　20     in the future.

1. A. beautiful　　　　　　 　　　　　　　　　　　　    B. unlimited　　　　　　

C. rare　　　　　　 　　　　　　　　　　　　　　　　　　  D. valuable

2. A. common　　　　　　 　　　　　　　　　　　　   B. the same　　　　　　

C. changeable　　　　　　 　　　　　　　　　　　　    D. different

3. A. crowded　　　　　　 　　　　　　　　　　　　   B. small

C. dirty　　　　    　　　　　　　　　　　　　　　　　　  D. busy

4. A. protecting　　　　　　 　　　　　　　　　　　　 B. saving

C. polluting　　　　　　 　　　　　　　　　　　　　　   D. fighting

5. A. try　　　　　　 　　　　　　　　　　　　　　　　    B. continue　　　　　　

C. decide　　　　　　 　　　　　　　　　　　　　　　　  D. have

6. A. wonders　　　　　　 　　　　　　　　　　　　   B. realizes　　　　　　

C. considers　　　　　　 　　　　　　　　　　　　　　  D. discovers

7. A. poles　　　　　　 　　　　　　　　　　　　　　    B. boats　　　　　　

C. methods　　　　　　 　　　　　　　　　　　　　　   D. ideas

8. A. mountains　　　　　　 　　　　　　　　　　　　 B. the sea　　 

C. trees　　　　　　 　　　　　　　　　　　　　　　　    D. forests

9. A. continue　　　　　　 　　　　　　　　　　　　    B. have　　　　　　

C. ought　　　　　　 　　　　　　　　　　　　　　　　　　　　  D. act

10. A. grow　　　　　　 　　　　　　　　　　　　　　  B. plant　　　　　　

C. save　　　　　　 　　　　　　　　　　　　　　　　　　 D. cut

11. A. Thus　　　　　　 　　　　　　　　　　　　　　   B. However

C. Generally speaking　　　　　　 　　　　　　　　 D. Therefore

12. A. still　　　　　　 　　　　　　　　　　　　　　　　 B. even　　　　　　

C. also　　　　　　 　　　　　　　　　　　　　　　　　　  D. certainly

13. A. too many　　　　　　 　　　　　　　　　　　　 B. a few　　  　　   

C. some　　　　　　 　　　　　　　　　　　　　　　　    D. few

14. A. production　　　　　　 　　　　　　　　　　   B. pollution

C. population　　　　　　 　　　　　　　　　　　　　　 D. revolution

15. A. houses　　　　　　 　　　　　　　　　　　　　　　　   B. vegetables　　　　　　

C. food　　　　　　 　　　　　　　　　　　　　　　　　　 D. lives

16. A. fruit　　　　　　 　　　　　　　　　　　　　　    B. meat　　　　　　

C. fish　　　　　　 　　　　　　　　　　　　　　　　　　  D. grain

17. A. feeds　　　　　　 　　　　　　　　　　　　　　  B. increases　　　　　　

C. supplies　　　　　　 　　　　　　　　　　　　　　    D. helps

18. A. use　　　　　　 　　　　　　　　　　　　　　　　 B. stay　　　　　　

C. keep　　　　　　 　　　　　　　　　　　　　　　　　　 D. last

19. A. control　　　　 　　　　　　　　　　　　　　　　　　   B. born　　　　　　

C. plan　　　　　　 　　　　　　　　　　　　　　　　　　 D. reward

20. A. nature　　　　　　 　　　　　　　　　　　　　　 B.sea　　　　　　

C. planet　　　　　　 　　　　　　　　　　　　　　　　   D. forest