D

Many places in the world need more fresh water. Every country is trying to find ways to turn salt water into fresh water.

Why aren’t there many factories like the Symi factory?

In some places, the sun is not hot enough, or it does not shine every day.

In such places, other ways of heating sea water can be used. These ways cost more money, but they work faster than the sun. By boiling sea water with high heat, a lot of fresh water can be made quickly.

But heating is not only way to get fresh water fresh salt water. Other ways are tried.

One way is freezing (冷冻). The fresh part of salt water freezes first. To get fresh water, the bits of ice are taken out.

Which way is the best? The one that gives the most water for the least money. There may be a different way for each place.

Symi’s way seems very good for small, hot places. It does not make very much water at a time. But the factory is easy to build and costs little.

That is why people in many dry places talk about Symi.

16. From the passage we know that fresh water ________.

A. is needed in every country   B. can be found in many factories

C. can be used in many ways   D. is very important for factories

17. What is the writer mainly talking about in the passage?

A. Hot places and dry places.

B. The ways of making fresh water from sea water.

C. How to make good use of sun.

D. Water-making factories in different countries.

18. The Symi factory ________.

A. is a fresh-making factory   B. can be build everywhere

C. can make much fresh water at a time D. does not need sunshine every day

19. Which is the best way for small and hot places to get fresh water?

A. Boiling or heating the sea water.  B. The way in hotter and drier places.

C. The Symi’s way.     D. Freezing the sea water in cold places.

20. Which of the following is wrong?

A. Many ways are tried to get fresh water.

B. A lot of water can be made quickly by heating.

C. The best way is to get more fresh water with the least money.

D. The Symi’s way does not work in dry places.