（    ） 10.A. sitting              B. sleeping                  C. waiting

（A）

       Many places in the world need more fresh（淡的）water. Every country is trying to find ways to turn salt water （海水） into fresh water. Why aren't there many factories like the Symi factory?

       In some places, the sun isn't hot enough, or it doesn’t? shine every day. In these places, other ways of heating （加热） sea water can be used. These ways cost more money, but they work faster than the sun. By boiling （煮沸） sea water with high heat, a lot of fresh water can be made quickly.

      But heating is not the only way to get fresh water from salt water. Other ways are tried. One way is freezing （冷冻）. Tile fresh part of salt water freezes first. To get fresh water, the pieces of ice are taken out. Which way is best? The one that gives the most Water for the least money is. It may be al different way for each place. Symi's way seems very good for small, hot places. It doesn't make very much water at a time. But the factory is easy to build and cost little.

       That's why people in many dry places talk about Symi!