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 seas. Nature has a great water system(系统).Rainwater finds its way to rivers and lakes. River water runs into the sea. At the mouths of the rivers, fresh water joins the salt water of the sea.
Here at the mouth of a river there is much important plant and animal life. But pollution destroys this life. We have to clean our rivers. Man has to work with nature, not against it.Water is like________.
A. clouds B. blood C. life ________ is in every living thing.
A. Blood B. Water C. SaltThe mouth of a river is near _________.
A. the sea B. a lake C. a mountain There is much plant and animal life at the _________ of a river.
A. head B. top C. mouthWe have to ________ our rivers.
A. find B. clean C. pollute