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 of asteroids whose orbits put them on a collision course with Earth.

Buy $ 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 form great nuclear fleet set against them," said a New York Times article.

1. 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.

2. What do scientists say about the collision of an asteroid 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.

3. 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.

4. 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

5. Which of the following best describes the author’s tone in this passage?

  A. Optimistic.        

B. Critical.        

C. Objective.       

D. Arbitrary.

参考答案Passage 6.        B       A       B       D      C

有科学家说，正如我们所知，如果我们现在不花钱定位小行星并防范它们，它们就会碰撞地球并摧毁生命。

小行星是掠过夜空的大型流星。它们大多数远离地球，环绕太阳运行，对我们没有威胁。但是也有成千上万颗小行星的轨道把它们引上与地球碰撞的方向。

马上买一批价值5000万美元的新型望远镜。然后25年内每年花1000万美元测定大多数宇宙巨石的位置。科学家说，等到我们发现一颗毁灭性的小行星时，我们有办法改变它的运行方向。

有些科学家造赞成用核武器使小行星偏离运行方向。但成本会很高。

值得吗？当判断会有什么风险时专家所考虑的两件事是：1）如果这种事件发生的可能性有多大；2）如果这种事件发生了，后果会多么严重。专家认为：一颗大到足以毁灭许多生命的小行星可能每五十万年才能撞击地球一次。听起来很少--但是，如果真有一颗掉下来，那就将是地球的末日。有一位科学家说：“如果我们不照顾这些大型小行星，它们就会来‘照顾’我们。”事情就这么简单。

然而，“治”可能比这“病”还糟糕。你真要核武器群布满全世界？纽约时报的一篇文章说：“世人对冲着它们所布置的庞大核武器的恐惧更甚于毁灭性巨石的恐惧。”