There are some objects in the sky that move so quickly that sometimes youonly see them out of the corner of your eye. These are some ofthe hugenumber ofbits of rock and dust that are floating around in space,calledmeteoroids.Normally, we cannotsee them at all, but if they travel too close to the Earth,they get caught bythe pull of the Earth, and beginto fall towards us. They fallfaster andfaster, until they hit ouratmosphere (大气层), by which timethey aregoing so fast that they begin to burn up, and all that you see is aflash oflight that moves very quickly across the sky and disappears. Theseshootingstars, or meteors as they are properly called, are quite common, andsometimesyou may see several in a night.

Most meteoroids are very small bits indeed, and they bum uplong before theyget to the Earth. However, a very few do manage to get all theway through theatmosphere, and actually fall to the ground. Usually they donot do much damage,although this is not always the case. Meteoroids that actuallymanage to reachthe Earth are called meteorites. Most countries have places where meteoriteshavestruck theEarth. Some of these places are very large indeed and aretouristattractions.

67. Why do some objects from outer space fall to theground?

[A] They are too big.

[B] They arc hit by huge rocks.

[C] They move too fast.

[D] They are pulled by the Earth.

68.What do we know about meteors from the text?

[A] They become a star in the sky.

[B] They are too small to be seen.

[C] They disappear very quickly.

[D] They do damage to the Earth.

69. What happens to most meteoroids coming into theatmosphere?

[A] They burn up.

[B] They fall to earth.

[C] They explode.

[D] The float in the air.

70. The word “meteorites” (Line 1, Para.3) refers to piecesof rock

that _____.

[A] move fast in outer space

[B] have been found at a tourist centre

[C] flash through space at a high speed

[D] have fallen onto the Earth from space

【答案及解析】

67.D 细节题。由原文第一段中的“Normally, we cannot see them at all, but if theytraveltoo close to the Earth, they get caught by the pull of the Earth, andbegin tofall towards us.”可知，有一些物体，通常我们根本看不见它们，但是如果它们离地球太近，受地球引力作用，它们就会落向地球。因此 D项“受地球引力作用”正确。

68.C 细节题。由原文第一段中的“they are going so fast that they begin to burnup, and allthat you see is a flash of light that moves very quickly across thesky anddisappears.”可知，它们下落的速度如此之快以至于它们开始燃烧，你只能看到一道光迅速划过天际，然后消失不见。即流星会很快消失，因此 C 项正确。

69.A 推理题。由原文第一段中的“They fall faster and faster, until they hitouratmosphere, by which time they are going so fast that they begin to burnup”可知，它们下落的速度越来越快，直到它们到达大气层，这时，它们的速度如此之快以至于开始燃烧。即流星体到达大气层时会燃烧。因此 A 项正确。

70.D 词义理解题。由原文第三段中的“Meteoroids that actually manage to reach the Eartharecalled meteorites.”可知，最后成功到达地面的流星体被称为陨石。因此 D 项正确。