D Unless we spend money to spot and prevent asteroids now, one might crash into Earth and destroy l——青夏教育精英家教网—

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Unless we spend money to spot and prevent asteroids (小行星) now, one might crash into Earth and destroy life as we know it, say some scientists.

Asteroids are bigger versions of the meteoroids (流星) that race across the night sky. Most orbit the sun far from Earth and don’t threaten us. But there are also thousands whose orbits put them on a collision course with Earth.

But &50 million worth of new telescopes right now. Then spend $10 million a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we’ll have a way to change its course.

Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn’t be cheap.

Is it worth it? Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500,000 years. Sounds pretty rare-but if one did fall, it would be the end of the world.　 If we don’t take care of these big asteroids, they’ll take care of us,” says one scientist. “It’s that simple.”

The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth? “ The world has less to fear from doomsday (毁灭性的) rocks than from a great nuclear fleet set against them,” said a New York Times article.

51. What does the passage say about asteroids and meteoroids?

A.　　　 They are heavenly bodies different in composition.

B. They are heavenly bodies similar in nature.

C. There are more asteroids than meteoroids.

D. Asteroids are more mysterious than meteoroids.

52. What do scientists say about the collision of a steroid with Earth?

A.　　　 It is very unlikely but the danger exists.

B.　　　 Such a collision might occur once every 25 years.

C.　　　 Collisions of smaller asteroids with Earth occur more often than expected.

D.　　　 It’s still too early to say whether such a collision might occur.

53. What do people think of the suggestion of using nuclear weapons to alter the course of asteroids?

A.　　　 It sounds practical but it may not solve the problem.

B.　　　 It may create more problems than it might solve.

C.　　　 It is a waste of money because a collision of asteroids with Earth is very unlikely.

D.　　　 Further research should be done before it is proved applicable.

54. We can conclude from the passage that ________.

A.　　　 while pushing asteroids off course nuclear weapons would destroy the world.

B.　　　 asteroids racing across the night sky are likely to hit Earth in the near future.

C.　　　 the worry about asteroids can be left to future generations since it is unlikely to happen in our lifetime

D.　　　 workable solutions still have to be found to prevent a collision of asteroids with Earth.

55. Which of the following best describes the author’s tone in this passage/

A. Optimistic　 B. Critical　 C. Objective　 D. Arbitrary

试题详情

Mail carriers will be delivering some good news and some bad news this week.

The bad news: Stamp prices are expected to rise 2 cents in May to 41 cents, the Postal Regulatory Commission announced yesterday. The good news: With the introduction of a “forever stamp,” it may be the last time Americans have to use annoying 2-or-3-cent stamps to make up postage differences.

Beginning in May, people would be able to purchase the stamps in booklets of 20 at the regular rate of a first-class stamp. As the name implies, “forever stamps” will keep their first-class mailing value forever, even when the postage rate goes up.

The new “forever stamp” is the United States Postal Service’s (USPS) answer to the complaints about frequent rate increases. The May increases will be the fifth in a decade. Postal rates have risen because of inflation (通货膨胀), competition from online bill paying, and the rising costs of employee benefits, including healthcare, says Mark Saunders, a spokesman for USPS.

The USPS expects some financial gain from sales of the “forever stamp” and the savings from not printing as many 2-or-3-cent stamps. “It’s not your grandfather’s stamp,” says Mr. Saunders. “It could be your great-grandchildren’s stamp.”

Other countries, including Canada, England, and Finland use similar stamps.

Don Schilling, who has collected stamps for 50 years, says he’s interested in the public’s reaction. “This is an entirely new class of stamps.” Mr. Schilling says. He adds that he’ll buy the stamps because he will be able to use them for a long period of time, not because they could make him rich — the volume printed will be too large for collectors. “We won’t be able to send our kids to college on these,” he says, laughing.

The USPS board of governors has yet to accept the Postal Regulatory Commission’s decision, but tends to follow its recommendations. No plans have been announced yet for the design of the stamps.

46. The main purpose of introducing a “forever stamp” is ______.

　 A. to reduce the cost of printing 2-or-3-cent stamps

　 B. to help save the consumers’ cost on first-class mailing

　 C. to respond to the complaints about rising postal rates

　 D. to compete with online bill paying

47. By saying “It could be your great-grandchildren’s stamp”, Mr. Saunders means that forever stamps _______.

　 A. could be collected by one’s great-grandchildren

　 B. might be very precious in great-grandchildren’s hands

　 C. might have been inherited from one’s great-grandfathers

　 D. could be used by one’s great-grandchildren even decades later

48. Which of the following is true according to the passage?

　 A. The investment in forever stamps will bring adequate reward.