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 need for water
3. remaining
is increased day by day. Only when steps are taken to deal with this problem immediate can we avoid a
4. increasing 5. immediately
severe worldwide water shortage later on. One of the first steps are to develop ways to reuse them .
6. is 7. it
Experiments have already∧ carried out in this field. The used water has been pumped to a water purifying
8. been
plant that it can be separated from waste matters and treated with chemicals so that it can be reused again .
9. where 10. 去掉again
