阅读电视广告词：“if we don’t save water,the last drop of water will be a tear-drop.”根据提示，写一篇60-80词的短文。
提示：
1.生活离不开水。
2.可饮用水在减少。
3.水污染严重。
4.应保护水源，再利用水。
       water is very important to humans.we can’t live without water.the water we can drink is falling.but some people don’t seem to care about it.they waste a lot of water.they pour dirty water into rivers and lakes.water pollution is getting more and more serious.so we must do something to stop the pollution.we not only protect the water but also find ways to reuse it.if we don’t do this,the last drop of water will be a tear-drop.