as we all know, plants and animals need water. so do the people's life and production, t,ife couldn't go on without water.

　　with the rapid development of agriculture and industry, more and more water is needed. therefore, water is becoming scarce in many places. what's more, a lot of rivers and lakes are beginning polluted by the waste watcr from factories. fish can't live in them any longer. at the same time, thc waste water does great harm to people's health.

　　in order to make rivers and lakes clean and prevent water from being polluted,we must do something to stop all sorts of pollution.