Unless we spend money to spot and prevent asteroids now.one might crash into Ear

Unless we spend money to spot and preventasteroids now，one mightcrash into Earth and destroy life as we know it，saysome scientists.

Asteroids are bigger versions ofthe meteoroids(流星)thatrace across the night sky. Most orbit the sun far from Earth and don't threatenus. But there are also thousands whose orbits put them on a collision coursewith Earth.

Buy $ 50 million worth of new telescopesright now. Then spend $ 10 million a year for the next 25 years to locate mostof 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 pushingasteroids off course with nuclear weapons. But the cost wouldn't be cheap. Isit worth it? Two things experts consider when judging any risk are: 1) Howlikely 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 Earthonce every 500,000 years. Sounds pretty rare-but if one did fall，it would be the end of the world. “Ifwe don't take care of these big asteroids，they'll takecare of us,” says one scientist. “It's that simple.”

The cure，though，mightbe worse than the disease. Do we really want fleets of nuclear weapons sittingaround 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.

1.What does the passage say aboutasteroids and meteoroids?

    A. They areheavenly bodies different in composition.

    B. They areheavenly bodies similar in nature.

    C. There aremore asteroids than meteoroids.

    D. Asteroidsare more mysterious than meteoroids.

2. What do scientists say aboutthe collision of an asteroid with Earth?

    A. It is veryunlikely but the danger exists.

    B. Such acollision might occur once every 25 years.

    C. Collisionsof smaller asteroids with Earth occur more often than expected.

    D. It's stilltoo early to say whether such a collision might occur.

3. What dopeople think of the suggestion of using nuclear weapons to alter the course ofasteroids?

    A. It sounds practical butit may not solve the problem.

    B. It may create moreproblems than it might solve.

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

    D. Further research shouldbe done before it is proved applicable.

4.We can conclude from the passage that________ .

    A. while pushing asteroidsoff course nuclear weapons would destroy the world

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

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

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

5.Which of the following best describes theauthor's tone in this passage?

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

试题答案

【答案】

1..B

2..A

3..B

4..D

5..C

【解析】 略