C
The world is not only hungry, but also thirsty for water. This may seem strange to you, since nearly 75 percent of the earth’s suce is covered with water. But about 97 percent of this huge amount is seawater, or salt water. Man can only drink and use the other 3 percent—the fresh water that comes from rivers and lakes. Some of it has been polluted and unfit for drinking.
However, as things stand today, this small amount of flesh water is still enough for us. But our need for water is increasing rapidly almost day by day. Only if we take steps to deal with this problem now, can we avoid (避免) a serious worldwide water shortage later on so we all have to learn how to stop wasting our precious water.
One of the steps we should take is to develop ways of reusing water. Today in most large cities water is used only once and then discharged (使流走). But it is possible to purify (净化) the water so that it can be used again.
But even if every large city purified end reused its water, we still would not have enough; where could we turn next To the oceans! That is certainly a possible solution. All we’d have to do is to remove the salt. This process is already in use in many parts of the world.
The author thinks that ______.