21.  First, we should make everyone realize the shortage of fresh water, call on people don't waste water .

22.  And people who waste fresh water should be punnished .

23.  The first , don't waste fresh water.

24.  Second, we should perswerade other people not to waste fresh water, at last , we should call on the society not waste water and prevent from the polution of water.

25.  Don't waste a little water.

26.  So we should not waste water.

27.  As long as we don't waste fresh water, I think, we can avoid this problem.

28.  They waste water, pollute water, and don't realize that there are many countries being short of fresh water, especially, in Africa.

29.  " So you want to be alive, first of all, please don't waste fresh water.

30.  We should not waste water.