今年的3月22日是第二个世界水日，世界淡水资源短缺日渐严重，联合国确定自去年起每年的这个日子为世界水日，旨在使全世界都来关心并解决这一问题。否则，水危机很可能会比粮食危机或石油危机更早到来。世界淡水资源是有限的。全球淡水总储量为3．5亿亿立方米，但人类生产与生 This year’s March 22 this year marks the second World Water Day. As the world’s freshwater resources become increasingly scarce, the United Nations has set a target of World Water Day every year since last year, aiming at making the world care and solve this issue. Otherwise, the water crisis is likely to come earlier than the food crisis or the oil crisis. The world’s freshwater resources are limited. The world’s total freshwater reserves of 3.5 billion cubic meters, but human production and students