For thousands of millions of years the moon has been going round the earth.At that time，the moon was the __1__ satellite(衛(wèi)星)of the earth.Today，__2__，the earth has many other satellites.All of them are __3__ by man.These man­made satellites are very much smaller than the moon.However，some of them will still be going __4__ the earth thousands of years from now.

　　Man­made satellites don't __5__ because they are going too fast to do so.As they speed along，they __6__ to go straight off into space.They __7__ out of the earth，or its gravity，which __8__ them from doing this.As a result，they travel in an orbit(軌道)round the earth.

　　If a man­made satellite travels about at a certain height，it can keep going __9__ round the earth，just like the moon.This is __10__ it is above the atmosphere(大氣)，and there is nothing to __11__ it down.If it travels __12__ than that，it will be slowed down so much that it will __13__ the earth.

　　Men have __14__ spaceships to the moon and to the two __15__ planets Mars(火星) and Venus(金星).By putting a camera on __16__ the spaceship to the moon，men have been able to __17__ photographs of the other side of the moon.This side is always __18__ from us as the moon __19__ the earth.The __20__ were later transmitted by radio to the earth.They showed that the other side of the moon is very much the same as the side that turns towards us.

　　1.A.first B.second

　　C.last D.only

　　答案：D　從常識以及下文的many other satellites可知在人造衛(wèi)星之前月亮是地球唯一(only)的衛(wèi)星。

　　2.A.then B.however

　　C.though D.so

　　答案：B　前后兩句間有轉(zhuǎn)折關(guān)系，所以用副詞however“然而”。

　　3.A.found B.discovered

　　C.made D.sent

　　答案：C　根據(jù)下文These man­made satellites可知這些衛(wèi)星是人造衛(wèi)星。

　　4.A.with B.round

　　C.behind D.after

　　答案：B　根據(jù)上文going round the earth可知這些衛(wèi)星繞著地球轉(zhuǎn)。

　　5.A.fall B.rise

　　C.break D.stop

　　答案：A　根據(jù)下文的they travel in an orbit round the earth.可知這些人造衛(wèi)星由于速度快所以不會掉(fall)下來。

　　6.A.want B.wish

　　C.hope D.tend

　　答案：D　當加速時，衛(wèi)星易于(tend to)進入太空。

　　7.A.pull B.push

　　C.take D.launch

　　答案：A　衛(wèi)星離開(pull out of)地球，進入軌道。

　　8.A.protects B.keeps

　　C.makes D.discourages

　　答案：B　地球重力阻止衛(wèi)星離開地球。keep...from doing...“阻止……做某事”。

　　9.A.in and in B.on and on

　　C.out and out D.up and up

　　答案：B　從上文可知衛(wèi)星會一直繞著地球轉(zhuǎn)。on and on“不停地”。

　　10.A.because B.why

　　C.whether D.when

　　答案：A　本句介紹前句的原因。This is because...“這是因為……”。

　　11.A.hand B.force

　　C.slow D.bring

　　答案：C　根據(jù)上下文可知大氣會使衛(wèi)星慢下來。slow sth.down“使……慢下來”。

　　12.A.higher B.longer

　　C.more D.lower

　　答案：D　與上文above the atmosphere構(gòu)成對應(yīng)，所以使用lower。

　　13.A.leave away B.fall to

　　C.go after D.knock over

　　答案：B　根據(jù)第二段第一句可知如果它的速度慢下來，衛(wèi)星會掉入(fall to)地球。

　　14.A.gave B.offered

　　C.sent D.drove

　　答案：C　人們已經(jīng)把宇宙飛船送上(send)了月球。

　　15.A.nearest B.smallest

　　C.biggest D.closest

　　答案：A　由常識可知Mars(火星)and Venus(金星)是最近的(nearest)兩個星球。closest表示“最靠近的”。

　　16.A.board B.right

　　C.left D.top

　　答案：A　board the spaceship“在宇宙飛船上”。

　　17.A.form B.film

　　C.catch D.take

　　答案：D　take photographs of“拍照”。

　　18.A.far B.hidden

　　C.different D.separated

　　答案：B　根據(jù)下文可知the other side of the moon是月球背朝地球的那一面。

　　19.A.leads B.obeys

　　C.circles D.pursues

　　答案：C　月球圍繞(circle)地球轉(zhuǎn)。

　　20.A.information B.letters

　　C.sounds D.photos

　　答案：D　根據(jù)上文提到的photographs可知將照片(photos)發(fā)回地球