71.  Some May be black or white, some May be yellow or brown, some are black and white.

72.  College student May getting to know the world outside the campus.

73.  Second, we May take oursevle into the world outside the campus.

74.  On the other hand, we May join all kinds of social ativities , this is the direct way we know the society better .

75.  People ever thought fresh water is countless, it May come from many sources, such as rain, river, well.

76.  We May use it as much as we want to.

77.  Secondly, we have to take all measures to protect them from being polluted and try our best to make use of the polluted water lastly , we May fall on the chemical techonoly that will make us get more fresh water from oceans.

78.  They May think in most places on earth there is plenty of rain.

79.  They May also hold that rivers and wells can provide us with enormous water.

80.  People May think that fresh water can't be used up.