题目内容：

阅读下面的短文,根据短文内容及首字母提示,在短文空白处填上一个适当的词,使短文完整、通顺,语法正确。

Although the world is hungry, it is even thirstier. While nearly 3/4 of the earth is c1. with water, we are short of drinking water. This is because about 97% of the water on the earth is sea water.

How can we a2. a serious water shortage? First, we should save water and not waste it. Then, we should protect our water resources and not pollute them. Lastly, we should discover ways to reuse water. Scientists have got some achievements in this field. But people's need for water is increasing day by day. We s3. don't have enough water. What else can we do?

The sea seems to have the best answer. There is p4. of water in the sea. But we need to take the salt away from the sea water. This is very expensive. If scientists can find c5. ways to do it, we can solve the problem of the shortage of water.