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A Thirsty World

The world is not only hungry;it is also thirsty for water. This may seem strange to you since nearly 75%of the earth's surface is     31    with water. But about 97%of this huge amount is sea-water, or salty water. Man can only drink and use the other 3%—the  ____32___ water that comes from rivers, lakes, underground, and other sources. And we cannot even use all of that, because some of it is in the form of icebergs and glaciers. Even  ____33___, some of it has been polluted.

At the moment, this small amount of fresh water is still enough for us. However, our demand for water is increasing     34    Only if we take steps to deal with this problem now can we avoid a severe worldwide water  ____35___ later on.

In addition to stopping wasting our precious water, one useful step we should take is to     36   ways of reusing it.

Today, in most large cities, water is used only     37    and it eventually returns to the sea or runs into underground storage tanks, But it is  ____38___ to pipe water that has been used to a purifying (净化) plant, There it can be filtered and treated with chemicals so that it can be used again just as if it were fresh from a spring.

But even if every large city purified and     39    its water, we still would not have enough. Where could we turn next?To the oceans!We can make use of the vast amount of sea-water by re-moving the salt. This salt-removing     40    is already in use in many parts of the world.

A. used	B. fresh	C. develop
D. process	E. possible	F. shortage
G. worse	H. reused	I. rapidly
J. covered	K. new	L. once

There has been a change in doctors' understanding of the cause of stomach ulcers.

• A、True
  
  

• B、 False
  
  

• C、 Not Given
  
  

Stomach ulcer can lead to stomach cancer.

• A、True
  
  

• B、False 
  
  

• C、Not Given