自然科学篇：The new way of getting fresh water

Have you ever seen the new way of getting fresh water? Here is an example. First， people make some long ponds(池塘) which are about half a meter deep. Then they put a cover(盖子) over each pond. The cover is made of glass that you can see through.

At night, sea water is taken into the ponds.The next day, the hot sun shines through the covers.The sun light turns the water into vapor(水蒸气) that goes up from the ponds. As it goes up, the vapor becomes mist(薄雾).On the inside of each cover the little drops of mist run together to make big drops.

People then collect these big drops through a special conduit(管道). Then the ponds are ready for the next day's work. As we know, the covers and other parts of the ponds cost very little. Sea water and the sun cost nothing. So this new way of getting fresh water seems wonderful.