问题补充：
The earth is our home and we must take good care of it. That is to say we must 1the land, air and water clean. But man 2a lot of pollution on earth since he first made fire, washed his clothes in the river and threw rubbish on the ground. Many years ago, pollution was not so serious 3there were not so many people.
There were enough 4air, land and water. When the land or the river was dirty in one place, man moved to 5place. Man is 6the whole world now. So there is 7enough clean air, nor clean land, nor clean water now. The more people there are in one place, 8environment they maybe have.
Perhaps you are afraid 9is endless(无休止的) for people to produce pollution.
10, we are glad to tell you that people have come to know the danger of pollution. And you can find more and more people are working hard to protect our earth.
【小题1】A．haveB．takeC．watchD．keep【小题2】A．producedB．has producedC．is producingD．will produce【小题3】A．soB．ifC．becauseD．but【小题4】A．cleanB．oldC．dirtyD．new【小题5】A．otherB．the otherC．anotherD．others【小题6】A．polluteB．pollutingC．clearingD．clear【小题7】A．neitherB．bothC．eitherD．none【小题8】A．the worstB．the worseC．the badD．worse【小题9】A．thatB．thisC．what D．it【小题10】A．QuicklyB．EspeciallyC．LuckilyD．AnywayD
答案：
(答案→)D
解析：这篇文章讲述了地球是我们的家，但是它现在已经受到了严重的污染，幸运的是，现在人们已经开始认识到污染的危害性，越来越多的人正在努力保护地球。
【小题1】A. have有 B. take带走 C. watch观看 D. keep保持由上句take good care of it可知我们应该保持地球清洁。故选D
【小题2】根据句意：自从第一次有了火之后，人类已经对地球产生了很多的污染。由后面的since he first made...可知用现在完成时。故选B
【小题3】A. so所以 B. if如果 C. because因为 D. but但是根据句意：很多年前，污染没有这样严重，是因为以前没有那么多的人。下句和上句是因果关系，故用because。故选C
【小题4】由上文中there were not so many people可知过去有足够清洁的空气、大地和水。故选A
【小题5】根据句意：当一个地方的土地和河水被污染之后，人们就会搬到另一个地方。one... another 意为“一个……另一个”。故选C
【小题6】根据句意:人们现在正在污染整个地球。be + doing 表示现在进行时故选B
【小题7】根据句意:现在既没有足够清新的空气，也没有清洁的土地和水。neither ...nor... 意为“既不……也不……”。故选A
【小题8】根据句意：一个地方的人越多，那个地方的环境就越糟糕。“the+比较级+其他，the+比较级+其他”表示“越……,越……”。故选B
【小题9】根据句意：或许你害怕人们会无休无止的产生污染。it 在宾语从句中作形式主语。故选D
【小题10】A. Quickly很快地 B. Especially特别地 C. Luckily幸运地 D. Anyway无论如何根据句意：幸运的是，人们现在已经开始知道了污染的危害性。故选C
