关于节约的英语作文
Theworldisnotonlyhungry,butalsothirstyforwater.Thismayseemstrangetoyou,sincenearly75%oftheearth'ssurfaceiscoveredwithwater.Butabout97%ofthishugeamountisseawater,orsaltwater.Mancanonlydrinkandusetheother3%--thefreshwaterthatcomesfromrivers,lakes,underground,andothersources.Andwecannotevenuseallofthat,becausesomeofitisintheformoficebergsandglaciers.Evenworse,someofithasbeenpolluted.
However,asthingsstandtoday,thissmallamountoffreshwater,whichisconstantlybeingreplacedbyrainfall,isstillenoughforus.Butourneedforwaterisincreasingrapi(dly--almostdaybyday.Onlyifwetakestepstodealwiththisproblemnowcanweavoidasevereworldwidewatershortagelateron.Alimitedwatersupplywouldhaveabadeffectonagricultureandindustry.Letmegiveyoujustonesmallexampieofhownecessarywateristoindustry.Didyouknowthattoproduceasingletonofsteel,ittakesabout91,000litersofwater?
Weallhavetolearnhowtostopwastingourpreciouswater.Oneofthefirststepsweshouldtakeistodevelopwaysofreusingit.Experimentshavealreadybeendoneinthisfield,butonlyonasmallscale.Forus,thesystemsareasimportantasthespacecraft.