6．
阅读理解
Water is very important to us. We cannot
live without it.
There is a lot of water on the Earth, but we
cannot use most of it. About 97. 5% of the Earth's water is salty. Most of the
fresh water is snow and ice near the North and South Poles(极).
We can only use less than one per cent of
the water on the Earth. We use water from both lakes and rivers. Some of the
water evaporates and then becomes rain. Of course we use rain water for farms
and other things. We use this water again and again.
Sometimes the Earth's water is in the wrong
place. There is a lot of rain in the tropics(热带地区)，but it is difficult to
have farms in the tropics. Most of the land there is not very rich. Some desert
land is rich, but there is only a little water in the desert.
Water is a problem for many people in the
world.
