8. Which of the following is closest in meaning to the phrase "leveled off" in the paragraph 2?

A. Reached its lowest level in popularity.   B. Stopped being popular.

C. Stopped increasing in popularity.   D. Become very popular.

C

Unless we spend money spotting and preventing 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 doing so? 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 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 (世界末日) rocks than from a great nuclear fleet set against it," said a Nero York Times article.

4. The title that best expresses the main idea is     .

A. Psychology of Infants                  B. Beauty in Variety

C. Beauty and Race             D. Beauty in Infants

B

America is a country on the move. In unheard-of numbers, people of all ages are exercising their way to better health. According to the latest figures,  59 per cent of American adults exercise regularly-up 12 percent from just two years ago and more than double the figure of 25 years ago. Even non-exercisers believe they would be more attractive and confident if they were more active.

It is hard not to get the message. The virtues of physical fitness are shown on magazine covers, postage stamps, and television ads of everything from beauty soaps to travel books. Exercise as a part of daily life did not catch on until the late 1960s when research by military doctors began to show the health benefits of doing regular physical exercises. Growing publicity ( 宣传) for races held in American cities helped fuel a strong interest in the ancient sport of running. Although running has leveled off in recent years as Americans have discovered equally rewarding--and sometimes safer-forms of exercise, such as walking and swimming, running remains the most popular form of exercise.

As the popularity of exercise continues to mount, so does scientific evidence of its health benefits.  The key to fitness is exercising the major muscle groups vigorously (强有力地) enough to approximately double the heart rate and keep it doubled for 20 to 30 minutes at a time. Doing such physical exercises three times or more a week will produce considerable improvements in physical health in about three months.

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