The world is not only hungry, but also thirst. This may sounds strange, since nearly seventy percent
1.thirsty 2.sound
of the earth"s surface is covered with water. But about ninety percent of this is sea water. Man and
most of the animals can only drink and use the remained ten percent of water --- fresh water. The
3. remaining
need for water is increased day by day. Only when steps are taken to deal with this problem immediate
4. increasing 5. immediately
can we avoid a severe worldwide water shortage later on. One of the first steps are to develop ways
6. is
to reuse them. Experiments have already ∧carried out in this field. The used water has been pumped to
7.it 8. been
a water purifying plant that it can be separated from waste matters and treated with chemicals so that
9. where
it can be reused again.
10.again去掉
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