21. In the long run, the most difficult problem caused by population growth on earth will probably be the lack of______.

　　A. food B. oil

　　C. space D. resources

　　22. Carl Sagan believes that Venus might be colonized from earth because______.

　　A. it might be possible to change its atmosphere

　　B. its atmosphere is the same as the earth's

　　C. there is a good supply of water on Venus

　　D. the days on Venus are long enough

　　23. On Venus there is a lot of______.

　　A. water B. carbon dioxide

　　C. carbon monoxide D. oxygen

　　24. Algae are plants that can______.

　　A. live in very hot temperatures B. live in very cold temperatures

　　C. manufacture oxygen D. all of the above

　　25. Man can eventually land on Venus only when______.

　　A. the algae have done their work B. the atmosphere becomes cooler

　　C. there is oxygen D. it rains there

　　21. C 22. A 23. B 24. D 25. D

　　It is doing something better than other people that makes us unique. Yet a surprising number of people still see individuality as a surface thing. They wear bright clothes, dye their hair strange colors and decorate their skin with tattoos (文身) to make some kind of social statement.

　　The whole purpose of individuality is excellence. The people who comprehend the simple principle of being unique through performance make our entire political and economic system work. Those who invent, who improve, who know more about a subject than other people do, and who take something that doesn't work and make it work—these people are the very soul of capitalism.

　　Charles Kettering didn't like the idea of cranking a car to make it start, so he invented the electric starter. Henry Ford figured out the assembly-line technique and made it possible to mass-produce automobiles. Lewis Waterman saw no need to go on dipping a pen into an inkwell, so he put the ink into the pen. George Westinghouse told the world how to stop a train, and Elisha Otis, inventor of the elevator, indirectly created the city skyline. These people understood that individualism means working at the top of one's capacity.

　　Fortunately, enough Americans have been inspired to do something with their uniqueness that we have developed in less than three centuries from a frontier outpost into not only a country of freedom but a country strong enough to protect that freedom. These people prized the notions of individuality and excellence above all things and thus kept the great machine functioning. The ones with the purple hair and the horrorable jewelry are just along for the ride, trying to be "different" and not knowing how to go about it.

　　The student who earns A's on his report card has grasped the idea and has found the real meaning of individuality. So has the youngster who has designed his own spaceship, who paints pictures of the world around him, or who can name all the states and their capitals. According to the author unique individuals are persons who______.

　　A. do something better than other people

　　B. know more about a subject than other people

　　C. excel others in work

　　D. all of the above

　　People who regard individuality as a surface thing always do the following EXCEPT

　　A. wearing bright clothes B. coloring their hair

　　C. doing better than others D. decorating their skin with tattoos

　　Which is NOT TRUE according to the passage?

　　A. Henry Ford invented assembly-line technique.

　　B. Elisha Otis was the inventor of the lift

　　C. George Westinghouse created cranks.

　　D. Lewis Waterman put the ink into the pen.

　　It can be inferred from the passage that______.

　　A. the real secret to being unique lies in our excellent work

　　B. if we want to be different we'd gain more profit

　　C the student who earns A's on the report card has not grasped the real meaning of

　　individuality D. all Americans work miracles In the writer's opinion who has understood the sense of individuality?

　　A. The youngster who designed his own spaceship.

　　B. The youngster who painted worthy pictures.

　　C. The youngster who was interested in wearing strange clothes.

　　D. Both A and B.

　　26. D 27. C 28. C 29. A 30. D