Question

2．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 20ton 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 20years 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!

76．What is the main idea of the article？（Please answer within 10words．）
How to Save Earth from a Collision with an Asteroid
77．How should we save earth from a collision in real life？（Please answer within 10words．）
Pull the asteroid off course
78．Express the meaning of the underlined sentence in another way．
The spacecraft would spend about a year drawing an asteroid away from Earth's path．
79．What does it in the first paragraph refer to？
An asteroid is rushing toward Earth．
80．Please fill in the blank with proper words or phrases．（Please answer within 10words．）
If it does happen．

Answer 1

分析 本文主要讲述如何拯救地球以免行星撞击到地球．

解答 76．How to Save Earth from a Collision with an Asteroid
（评分要求：根据与文章整体内容的相关程度酌情给分．）
77．Pull the asteroid off course．
78．The spacecraft would spend about a year drawing an asteroid away from Earth's path．
79．An asteroid is rushing toward Earth．
80．If it does happen
76．How to Save Earth from a Collision with an Asteroid  主旨大意题．纵观整篇文章可以得知，本文讲述的是如何在小行星撞击地球时拯救地球．
77．Pull the asteroid off course．细节题．根据文章的第四段第一句和第五段的第二句可以得到答案．
78．The spacecraft would spend about a year drawing an asteroid away from Earth's path．细节题．根据前文The tractor could then use its own gravity to pull the asteroid off course可知the tractor 可以使用它的重力把小行星拉出轨道，本句的意思是宇宙飞船会花费大约一年的时间把小行星拉出地球的轨道．
79．An asteroid is rushing toward Earth．猜测词义题．根据文章第一段an asteroid（小行星） is rushing toward Earth．可知可怕的场景是一个小行星正撞向地球．
80．If it does happen  填空题．根据前面提到的这种几率非常之小和后面的"然而"（though）判断，这儿应该填"如果的确发生了（If it does happen）"．

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