水资源短缺问题

提纲

　　1. 水的重要性。

　　2. 造成水资源短缺的原因。

　　3. 怎样缓解缺水问题及保护水资源。

　　People can't imagine life without water. Without it， the earth we live on would be a dead one. There would be no trees， no crops， no animals and no people. So water is considered to be next to oxygen in importance.

　　Although nearly three quarters of the earth's surface is covered with water， it is sea water and undrinkable. The demand for water is increasing， while water resources are scarce. Agricultural production needs enormous amounts of water， so does industry. Besides，the rapid growth of population makes it more and more difficult for people to survive because of the water shortage. So water shortage has become one of the most serious problems.

　　Fortunately， people have realized this pressing problem and are trying to find ways to salve it. First， people are urged to economize on water. Second， measures are taken to protect water resources. Third， circulating water is used for industrial purposes over and over in factovies and treated sewage water is used for irrigation in farming land.