The world is not hungry，but it’s thirsty. 1 while we say we are short of water.Why？Because about 97% of water on the earth is sea water which we can‘t drink or use for watering plants directly.Man can only drink and use the 3% of water that es from rivers and lakes. 2 ，because some of it has been polluted.
Now more water is needed.The problem is how we can avoid a serious water shortage in the future. 3 Scientists are making study in this field.Today，In most large cities water is used only once and then runs to the sea or rivers.but it can be used again.Even if every large city reused its water，the water will still not be enough. 4 .
The sea seems to give us the best answer.There is a lot of water in the sea.All that needs to be get the salt out of the sea water.This will be expensive，but it has already been used in many parts of the world. 6 So you see，if we can find out a way，we’ll be in no danger of drying up.
从方框中所给的选项中选出能填入空白处的最佳选项，补全短文。其中有一项为多余选项。A．Scientists are trying to find a cheaper way of doing it.B．It seems strange that nearly 3/4 of the earth is covered with water.C．What could people do next?D．We should use all the water directly.E. First, we should find out ways to reuse it.
F. And we can’t even use all of that.B
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(答案→)B
解析：
【小题1】上文提到地球想喝水，下文说地球缺水。根据连接词while，然而，可知选B，最符合逻辑关系。好像很奇快，地球的将近3/4覆盖着水。
【小题2】上文提到地球上大部分水不能直接使用，故选F，我们甚至不能全部利用他们。下文解释这种问题的原因。
【小题3】根据上文The problem is how we can avoid a serious water shortage in the future.我们怎样才能避免在将来发生严重的水资源短缺问题，结合下文有些水可以重复利用，可知选E，首先我们应该找出重新利用他的方法。
【小题4】结合上文出现的序数词first，以及下文介绍的利用海水，可知选C，可起到承上启下的作用。
【小题5】上文提到了利用海水的方法，但比较代价高，结合下文如果我们能找到一种方法，可知选项处为假设的前提，故选A。。