阅读表达

　　Movie producers love the idea, partly because it’s so afraid and partly because it could really happen．The scene is this：An asteroid(小行星)is rushing toward Earth．A collision is unavoidable．When this happens, lots of people will die．

　　In the movies, a brave hero thinks of a clever plan to destroy the asteroid and save Earth．In real life, scientists have come up with more reasonable plans that might actually work if this situation comes up．

　One way, say scientists and astronauts, is a 20 ton spacecraft called a gravitational tractor．First, the tractor, would move quickly up to the threatening asteroid and stop a short distance away．It would hang there, firing its thrusters just enough to fight the force of gravity between the spacecraft and the asteroid．

　　The tractor could then use its own gravity to pull the asteroid off course．It would take about a year for the spacecraft to draw an asteroid away from Earth’s path．

　　The question is that the spacecraft would have to arrive at the asteroid about 20 years before it hits Earth．It would be easier then to move the asteroid out of the way than it would be if the asteroid was near the Earth．

　　Still, the tractor idea is better than many ways proposed years ago for asteroid avoidance．Exploding asteroids, for example, wouldn’t work because the rocky bodies are too full of air．

　　Don’t spend too much time worrying about asteroids’ falling on your house, however．The chances of a collision happening in your lifetime are very small．If ________, though, scientists will do everything they can to keep you from getting hurt, sounds very heroic to me!

1．What is the main idea of the article?(Please answer within 10 words．)

________________________

2．How should we save Earth from a collision in real life?(Please answer within 10 words．)

________________________

3．Translate the underlined sentence in the fourth paragraph into Chinese．

________________________

4．Which sentence in the passage can be replaced by the following one?

Pulling the asteroid off course when it’s still far away from Earth is more easily carried out when it’s near the Earth．?

_________________________

5．Please fill in the blank with proper words or phrases．(Please answer within 10 words．)

__________________________