11.  Once you have learned how to deal with this kind of problems, you must do a lot of problems of this kind to add your practice.

12.  Then you can deal with this kind of problems with no problem .

13.  We ought to save water, deal with polution , these is the most important thing that we should do .

14.  We should know how to deal with it more than to be at a loss.

15.  The shortage of fresh water now becomes a very big problem that we have to deal with.

16.  In my opinion, we must take steps to deal with this problem immediately.

17.  Then, how can we do to deal with the problem?

18.  Of course, we must deal with the problem and manage it.

19.  Second, we must make measures to deal with this problem.

20.  What should we do to deal with this problem?