1. (2016高二下·西藏期末) 阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中选出最佳选项，并在答题卡上将该项涂黑。

    Water is the “life blood” of our earth. It is in every living thing. It is in the air. It runs through mountains and valleys. It forms lakes and oceans. Water is everywhere.

    Nature has a great water system. Rain water finds its way to streams and the oceans.

Here at the mouth of a river there is much important plant and animal life. Pollution destroys this life, so we have to clean out streams and rivers. Man has to work with nature—-not against it.

1. （1） According to the passage, water is the _______ of our earth.

   A . blood B . clouds C . rain D . life
3. （2） The mouth of the river is near ______.

   A . a stream B . the ocean C . the mountains D . valleys
5. （3） There is much plant and animal life at the __________.
   

   A . head of a river B . bottom of a sea  C . body of a stream D . mouth of a river
7. （4） The water in streams and rivers all comes from ______.
   

   A . rain B . nature C . valleys D . oceans