31.  Don't pollute fresh water again.

32.  Some fresh water are polluted.

33.  Finally, we must assure that fresh water shouldn't be polluted.

34.  It's reported that there is much fresh water was polluted every year .

35.  Second, we shall conserve fresh water source and fright against the action which pollute fresh water.

36.  With the development of the industries and agraculation , much fresh water is seriously polluted.

37.  And we can not polluted water.

38.  Secondly, we must expend more fresh water in industry as industry is devolpping , Thirdly, it is most important that more and more fresh water is polluted.

39.  Unfortunately, the very fresh water is polluted more and more seriously.

40.  Third, in these days, many fresh water has been polluted.