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状语从句状语从句指句子用作状语时，起副词作用的句子。它可以修饰谓语、非谓语动词、定语、状语或整个句子。根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。状语从句一般由连词(从属连词)引导，也可以由词组引起。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。1.时间状语从句(1)时间状语从句常用when,as（当..时候）,while,before,after,since,till,until,assoonas等连词来引导。例如：HehadlearnedalittleChinesebeforehecametoChina.Afterhefinishedmiddleschool,hewenttoworkinafactory.(2)在时间状语从句里，主句用将来时态时，从句通常不用将来时态，用现在时态表示将来的动作或状态。（主将从现）例如：I’llringyouupassoonasIgettoNewYork.Iwilltellhimeverythingwhenhecomesback.Hewon’tbelieveituntilheseesitwithhisowneyes.(3)在带有till或until引导的时间状语从句的主从复合句里，如果主句用肯定式，其含义是“一直到……时”，谓语动词只能用延续性动词。如果主句用否定式，其含义是“直到……才……”,“在……以前不……”,谓语动词可用瞬间性动词。例如：Theyoungmanreadtillthelightwentout.Let’swaituntiltherainstops.Wewon’tstartuntilBobcomes.Don’tgetoffuntilthebusstops.2.条件状语从句(1)条件状语从句通常由if,unless(除非)引导。例如：Whatshallwedoifitsnowstomorrow?Don’tleavethebuildingunlessItellyouto.(2)在条件状语从句里，谓语动词通常用现在时态表示将来的动作或状态。（主将从现）例如：（必考）I’llhelpyouwithyourEnglishifIamfreetomorrow.Hewon’tbelateunlessheisill.(3)“祈使句+and(or)+陈述句”在意思上相当于一个带有条件状语从句的复合句。例如：Hurryup,oryou’llbelate.=Ifyoudon’thurryup,you’llbelate.Studyhardandyouwillpasstheexam.=Ifyoustudyhard,youwillpasstheexam.3.原因状语从句(1)原因状语从句通常由because,since,as引导。例如：Hedidn’tcometoschoolbecausehewasill.Asitisraining,weshallnotgothezoo.Sinceyoucan’tanswerthequestion,I’llasksomeoneelse.(2)because表示直接原因，语气最强。Because引导的原因状语从句多放在主句之后。As和since语气较弱，一般用来表示明显的原因。由as和since引导的原因状语从居多放在句首。例如：------Whyaren’tgoingthere?------BecauseIdon’twantto.Ashehasnocar,hecan’tgetthereeasily.Sincewehavenomoney,wecan’tbuyit.(3)because和so不能同用在一个句子里。4.结果状语从句(1)结果状语从句由so…that,such…that引导。例如：Heissopoorthathecan’tbuyabikeforhisson.Sheissuchagoodteacherthateverybodylikesher.(2)so…that与such...that可以互换（可能会考）。例如：在由so...that引导的结果状语从句中，so是副词，与形容词连用。其结构是:“...so+形容词（副词）+that+从句”。例如：Motherlivessofarawaythatwehardlyeverseeher.在由such…that引导的结果状语从句中，such是形容词，它修饰的可以是单数或复数可数名词，也可以是不可数名词；名词前面可以带形容词，也可不带。如果是单数可数名词，前面需加不定冠词a或an。例如：Itwassuchahotdaythatnobodywantedtodoanything.有时上述两种结构是可以互换的。例如：Itwassuchawonderfulfilmthatallofuswantedtoseeitagain.=Thefilmwassowonderfulthatallofuswantedtoseeitagain.Itissuchanimportantmatchthatnobodywantstomissit.=Thematchissoimportantthatnobodywantstomissit.(3)如果名词前由many,much,little,few等词修饰时，只能用so,不用such。例如：Soonthereweresomanydeerthattheyateupallthewildroses.Hehassolittletimethathecan’tgotothecinemawithyou.5.比较状语从句比较状语从句通常由as…as（否定notso/as...as）,比较级+than…等连词引导。例如：TomrunsfasterthanJohndoes.Thisclassroomisasbigasthatone.6.目的状语从句(1)目的状语从句通常由sothat,inorderthat引导。例如：Westartedearlysothatwecouldcatchthefirsttrain.Hestudieshardsothathecouldworkbetterinthefuture.Weusedthecomputerinorderthatwemightsavetime.(2)sothat既可引导目的状语从句，又可引导结果状语从句。区别这两种从句的办法有两个：1)目的状语从句里往往带有情态动词can,could,may,might等。2)从意思上看，目的状语从句往往表示的目的很明确。例如：Speakclearlysothattheymayunderstandyou.(目的状语从句)Jackisbadlyillsothathehastorest.(结果状语从句)7.让步状语从句(1)让步状语从句通常由although,though等连词引导。例如：Thoughheisyoung,heknowsalot.AlthoughIamtired,Imustgoonworking.(2)although(though)与but不能用在同一个句子中。例如：我们不能说：Thoughitwasraininghard,buthestillwentout.应该说：Thoughitwasraininghard,hestillwentout.或Itwasraininghard,buthestillwentout.8.地点状语从句地点状语从句常常由where来引导。例如：Gowhereyoulike.Wherethereisawill,thereisaway.易混引导词while,when的区别：1.when既可以指时间点,与瞬间动词连用，也可以指时间段，与延续性动词连用（=while）。如：Whenhecamein,hismotherwascooking.When(While)wewereatschool,wewenttothelibraryeveryday.While表示时间段,因此，while从句的谓语动词要用延续性动词。如：Pleasedon'ttalksoloudwhileothersareworking.2．Because,as,since的区别：Because用于表示直接原因,回答why提出的问题，语气最强；As用于说明原因,着重点在主句，常译成由于；since表示显然的或已知的理由或事实，常译成既然。如：Waterisveryimportantbecausewecan'tlivewithoutit.Hedidn'tcomeyesterdayashismotherwasill.I'lldoitforyousinceyouarebusy.【实例解析】1.Youwillstayhealthy_______youdomoreexercise,suchasrunningandwalking.A.ifB.howC.beforeD.where2.---Shallwegoonworking?---Yes,_________Iprefertohavearest.A.whenB.ifC.becauseD.though3.Noneofusknewwhathadhappened_________theytoldusaboutit.A.whenB.untilC.afterD.though4.---Ihopeyou’llenjoyyourtrip,dear!---Thankyou,mum.I’llgiveyouacall_________Igetthere.A.untilB.assoonasC.sinceD.till考点精炼一.单项填空1._______he’sold,hecanstillcarrythisheavybag.A.ThoughB.SinceC.ForD.So2.---Doyouknowifhe_______toplaybasketballwithus?---Ithinkhewillcomeifhe______freetomorrow.A.comes;isB.comes;willbeC.willcome;isD.willcome;willbe3.Inthezooifachild_____intothewaterandcan’tswim,thedolphinsmaycomeup______him.A.willfall;tohelpB.falls;tohelpC.willfall;helpD.falls;helping4.Idon’tremember________heworkedinthatcitywhenhewasyoung.A.whatB.whichC.whereD.who5.Wewillstayathomeifmyaunt________tovisitustomorrow.A.comesB.comeC.willcomeD.iscoming6.Thepoliceaskedthechildren_______crossthestreet________thetrafficlightsturnedgreen.A.not;beforeB.don’t;whenC.notto;untilD.not;after7.Iwaslateforclassyesterday_______therewassomethingwrongwithmybike.A.whenB.thatC.untilD.because8.I’llgoswimmingwithyouifI________freetomorrow.A.willbeB.shallbeC.amD.was9.Intheexam,the________youare,______the_______mistakesyouwillmake.A.careful;littleB.morecareful;fewestC.morecareful;fewerD.morecareful;less10.Youshouldfinishyourlessons_______y