11.  I couldn't use it freely.

12.  For example, in summer, in our apartment, we can not use fresh water in the noon.

13.  In fact, we can not use the sea water because it is made up of too salt, and we only can use the fresh water.

14.  A lot of water of the river and the well is not used .

15.  In some places, the rain water is even not used .

16.  Third, that the prolution make a lot of fresh water can't be used.

17.  We can't use sea directly.

18.  Third, but not last, we should not use some fresh water for only one time.

19.  In common view, fresh water will never be used out .

20.  Many of them won't use English in their future teaching.