一篇短文改错,自己改了一些,但不全,

一篇短文改错,自己改了一些,但不全,
Looking at the map of the world,and we can see that three quarters of the earth are covered by water.However,we are short of water,it sounds strange to you.But it is true.You see,97% of the total water in the world is sea water,which is so salt that man can drink it.So only 3% of the water can be drunk or used for man.And the drinkable water comes from rivers,lakes and underground.Man even can’t use them completely,because the water contains icebergs and glaciers.All what is the worst is that water in some parts has been polluted or is being polluted.How can we drink?So something must be done to protect water from polluted.