for-和-since-的区别

for和since的区别Since用来说明动作起始时间，for用来说明动作延续时间长度。Ihavelivedhereformorethantwentyyears.IhavelivedheresinceIwasborn..Myaunthasworkedinaclinicsince1949.Somenewoilfieldshavebeenopenedupsince1976.IhaveknownXiaoLisinceshewasalittlegirl.MybrotherhasbeenintheYouthLeaguefortwoyears.Ihavenotheardfrommyuncleforalongtime.JohnhasbeenhereinChinasincetwoweeksago.CommunicationsacrosstheAtlantichavedevelopedsteadilyforonehundredyears.Hehasbeentalkingabouttheaccidentsinceithappenedtwohoursago.IhaveworkedhardwithmyEnglishforallthethreeseniorhighyears.EnglishgrammarhasnotchangedmuchsincethetimeofShakespeare.CNNhasbeenontheairformorethanfifteenyears.注意：并非有for作为时间状语的句子都用现在完成时。Iworkedhereformorethantwentyyears.(我现在已不在这里工作。)Ihaveworkedhereformanyyears.(现在我仍在这里工作。)小窍门：当现在完成时+一段时间，这一结构中，我们用下面的公式转化，很容易就能排除非延续动词在完成时中的误使。1)(对)TomhasstudiedRussianforthreeyears.=TombegantostudyRussianthreeyearsago,andisstillstudyingitnow.2)(错)Harryhasgotmarriedforsixyears.=Harrybegantogetmarriedsixyearsago,andisstillgettingmarriednow.显然，第二句不对，它应改为Harrygotmarriedsixyearsago.或Harryhasbeenmarriedforsixyears.