Theworldisnotonlyhungrybutalsothirstyforwater.Thismayse...
问题详情：Theworldisnotonlyhungrybutalsothirstyforwater.Thismayseemstrangetoyou,sincenearly70%oftheearth'ssurfaceiscoveredwithwater.Butabout97%ofthatisseawaterorsaltwater.Mancanonlydrinkandusetheother3...