Sixty-five million years ago, an asteroid (小行星) that crashed on Earth led to the disappearance of the largest animals that have ever walked our planet – the dinosaurs. At least, this is what some scientists believe. But that accident happened so long ago. People have come to believe that we are free of threats from asteroids and everything else from space.
However, what happened on Feb 15 , 2013 was a reminder that we’re just as vulnerable as the dinosaurs once were. Two objects from space – a meteor (陨石) and an asteroid called 2012 DA14 – visited Earth’s atmosphere on the same day. The former fell in Russia, injuring 1,200 people, while the latter passed by Earth at a record-setting close distance.
Scientists had been expecting the asteroid since last year, but the meteor was a surprise. NASA’s telescope system only detects asteroids at least 50 meters in diameter (直径), which is just about the size of 2012 DA14. But the meteor was much smaller, which made it harder to spot.
But what if we do spot an asteroid that is headed right for Earth? There are several possible ways in which dangerous asteroids could be made to change its orbit. Which method is best depends on several factors and most importantly – how much time we have to stop it.
If there is enough time before the hit, we can send off a heavy spacecraft to travel alongside the asteroid. The gravity from the spacecraft would gradually change the rock’s orbit. Besides that, scientists could one day use sun-powered lasers to either make asteroids disappear or change their course. If there’s not enough time, we’ll have to go after the asteroid with a spacecraft and change its orbit with a crash. Finally, if things are truly desperate, there will be only one choice left – to use a nuclear bomb. That could turn the asteroid into a meteor shower, which would be even more dangerous.
小题1:The author mentioned the asteroid that led to the dinosaurs’ dying out to ______.
A．show that asteroids fall from space frequently
B．alert people about the possible danger of objects falling from space
C．inform readers about the constant threats the Earth faces
D．suggest that there are still many mysteries about the universe小题2:The underlined word “vulnerable” in the second paragraph probably means ______.
A．unprotected
B．lonely
C．stupid
D．self-important小题3:Which of the following statements is TRUE about the meteor that fell to the Earth in Russia?
A．It passed by the Earth at a close distance.
B．It was spotted by NASA’s telescope system a year ago.
C．It is about the same size as the asteroid that passed by the Earth.
D．It fell to the Earth and caused great damage to the local community.小题4:What is the main idea of the article?
A．Learning about asteroids and meteors.
B．The threats of objects from space and possible solutions.
C．NASA’s latest technology to discover visitors to the Earth from space.
D．How to measure the damage of collisions from asteroids and meteors.
小题1:B
小题2:A
小题3:D
小题4:B
题目分析：本文是一篇科技说明文。文章介绍了小行星和陨石可能对人类造成的伤害，以及人类为消除危害可能采取的措施和方法。
小题1:考查推理判断。根据文章第一段中的Sixty-five million years ago, an asteroid (小行星) that crashed on Earth led to the disappearance of the largest animals that have ever walked our planet – the dinosaurs.可知，作者引用小行星撞击地球导致恐龙灭绝这个事实，来警示人们小行星和陨石可能对地球造成严重危害的严重性。故选B。
小题2:考查推测词义。根据文章第二段中的we’re just as vulnerable as the dinosaurs once were.可知，我们就像从前的恐龙一样无助而灭绝。所以A正确。
小题3:考查细节理解。根据文章第二段中的The former fell in Russia, injuring 1,200 people可知，前一颗陨石落在了俄罗斯，造成1200受伤。因此和D项内容吻合。
小题4:考查主旨大意。纵观全文可知：第一段通过恐龙灭绝的事实，引起人们对小行星和陨石对人类造成的危害重视；第二段谈下落在俄罗斯的陨石造成的危害；第三、四、五段谈目前人类的观测技术及我们应对陨石危害的方法和措施。所以B项正确。