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

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问题     Unless we spend money to spot and stop asteroids (小行星) now, one might crash into Earth and destroy life as we know it, say some scientists. Asteroids are bigger 【B1】______ of the meteoroids (流星) that 【B2】______ across the night sky. Most orbit the sun far from Earth and don’t 【B3】______ us. But there are also thousands of asteroids whose orbits put them on a 【B4】______ course with Earth. Buy $ 50 million 【B5】______ of new telescopes right now. Then spend $10 million a year for the next 25 years to 【B6】______ most of the space rocks. By the time we 【B7】______ a fatal one, the scientists say, we’ll have a way to change its course. Some scientists favor 【B8】______ asteroids off course with nuclear weapons. But the cost wouldn’t be cheap.
    Is it worth it? 【B9】______ . Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500,000 years. 【B10】______ . "If we don’t take care of these big asteroids, they’ll take care of us," says one scientist. "It’s that simple."
    【B11】______ "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.
【B1】

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