(C)The earth is not only, but also thirsty for water. This may seem strange to you. because nearly 70% of the earth’s surface（表面）is covered with water. But about 97% of that is sea water, or salt water. Man can only use the other 3%—the fresh water from rivers, lakes, and other sources. And we can’t even use all of that, because some of it is in the form of icebergs and glaciers（冰川）. Even worse, some of it has been polluted. However, as things stand today, the fresh water is still enough for us. But our need for water is becoming larger and larger quickly—almost day by day. We should take steps to do with this problem now and in this way we can get away from a serious world-wide water shortage later on. We all have to learn how to stop wasting our valuable water, one of the first step is to develop ways of reusing it. Today in most large cities, water is used only once and then sent out into a sewer system(下水道), from there it returns to sea or runs into underground (地下)places. But even if every large city reused its water, we still would not have enough. All we’d have to do to make use of sea water in the world is to remove the salt. 小题1: The earth is thirsty for water because_______ .
(a) make good use of the sea water. (b) carry salt water into lakes and rivers. (c) try to save the fresh water as much as possible (d) do our best to use the water again. (e) drink and use all the water on the earth’s surface
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