11.  For these reasons, we should make good use of fresh water.

12.  But to those who try their best to protect, discover or make good use of it, we should award them metal or material trophies.

13.  But most of us aren't aware of making good use of it.

14.  From some books, we know that the total of fresh water of the earth don't increase for ever, only it can recycle , quicker if we make good use of it .

15.  We should be warned of making good use of fresh water.

16.  In order to ensure to ourselves plenty of fresh water, we should make good use of water.

17.  First, we should realize this point; Second, we ought to make good use of freash water; Third, we should protect freash water from being polluted; Finaly , we can get freash water from sea-water with the help of modern science.

18.  First, I think we should make good use of water.

19.  Facing the problem of shortage of fresh water, we should make good use of fresh water.

20.  First of all, we should make good use of fresh water and not waste it any longer.