尽管地球表面到处都是水,但其中98%都是咸的,真正可供人们利用的淡水只是地球总水量的万分之一.近年来,由于人口的增长,工农业生产的发展,致使用水骤增,再加上工业“三废”每年污染一百六十立方公里水,所以地球上这么一点淡水就越来越紧张了.如果再不采取新的 Although the surface of the earth is full of water, 98% of them are salty. The fresh water that can be used by people is only one ten-thousandth of the total water volume of the earth. In recent years, due to the growth of population, the development of industrial and agricultural production has led to the use of water. The sudden increase, coupled with industrial “three wastes” polluted 160 million cubic kilometers of water each year, so that a little fresh water on the earth becomes more and more nervous. If you do not take new ones