1.As we all know water plays an important part in people's daily lives.More and more water is needed in the modern society.So we should try to save it.
Now many places are short of water.For example,a big drought hit the Southwest of China at the beginning of this year.especially Yunnan province,milions of people has not got enough water for common life.A lot of rivers and lakes are polluted.What's worse,many people are wasting water seriously.
In order to protect water,let's do something to fight against all kinds of pollution and waste of water.
2.
The world is not only hungry,but also thirsty for water.This may seem strange to you,since nearly 75 % of the earth's surf-ace is covered with water.But about 97% of this huge amount is sea water,or salt water.Man can only drink and use the other 3% -- the fresh water that comes from rivers,lakes,underground,and other sources.And we cannot even use all of that,because some of it is in the form of icebergs and glaciers.Even worse,some of it has been polluted.
However,as things stand today,this small amount of fresh water,which is constantly being replaced by rainfall,is still enough for us.But our need for water is increasing ra almost day by day.Only if we take steps to deal with this problem now can we avoid a severe worldwide water shortage later on.A limited water supply would have a bad effect on agriculture and industry.Let me give you just one small exampie of how necessary water is to industry.Did you know that to produce a single ton of steel,it takes about 91,000 liters of water?
We all have to learn how to stop wasting our precious water.One of the first steps we should take is to develop ways of reusing it.Experiments have already been done in this field,but only on a small scale.For us,the systems are as important as the spacecraft.
