- Theworldisnotonlyhungry,butalsothirstyforwater.Thismayseemstrangetoyou,sincenearly75%oftheearth'ssurfaceiscoveredwithwater.Butabout97%ofthishugeamountisseawater,orsaltwater.Mancanonlydrinkandusetheother3%--thefreshwaterthatcomesfromrivers,lakes,u...
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