72英语语法基础知识――状语从句

状语从句（AdverbialClause）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。状语从句的种类用来修饰谓语动词、其它动词、定语、状语或整个句子的从句叫做状语从句。状语从句可分为：1.时间状语从句；(adverbialclauseoftime)2.地点状语从句；(adverbialclauseofplace)3.原因状语从句；(adverbialclauseofcause)4.条件状语从句；(adverbialclauseofcondition)5.目的状语从句；(adverbialclauseofpurpose)6.让步状语从句；(adverbialclauseofconcession)7.比较状语从句；(adverbialclauseofcomparison)8.方式状语从句；(adverbialclauseofmanner)9.结果状语从句。(adverbialclauseofresult)状语从句的时态特点一般情况下，时间和条件状语从句的谓语动词一般用“一般现在时”表示“一般将来时”，用“现在完成时”表示“将来完成时”。例如：IwillcallyouassoonasIarriveinBeijing.我一到北京就给你打电话。（这是由assoonas引导的时间状语从句，从句中的谓语动词arrive是一般现在时，表示一般将来时，决不可用willarrive）AssoonasIhavefinishedthiswork,Iwillgohome.我一完成此工作，就回家。（从句中的谓语动词用现在完成时havefinished，表示将来完成时,决不可用willhavefinished）Ifhecomesback,pleaseletmeknow.如果他回来了，请通知我。（从句中的谓语动词用comesback,表示一般将来时，决不可用willcomeback）状语从句讲解和练习状语修饰动词、形容词、副词或整个句子。通常由副词、介词短语、动词不定式、分词和从句等担当。例如：1.Naturally,ourgrandparentswerepleasedtogetourphonecall.(副词)2.Weworkedhard,fromsunrisetosunset.(介词状短语)3.Tohelpmydisabledaunt,Ispendanhourworkinginherhouseeveryday.(不定式)4.Seenfromadistance,thefarmhouselookeddeserted.(过去分词)5.IknowhowtolightacampfirebecauseIhaddoneitbefore.（原因状语从句）状语的位置比较灵活，可以位于句首、句末或句中。enough用作状语修饰形容词和副词时必须后置。状语从句主要用来修饰主句或主句的谓语。一般可分为九大类，分别表示时间、地点、原因、目的、结果、条件、让步、比较和方式。尽管种类较多，但由于状语从句与汉语结构和用法相似，所以理解和掌握它并不难。状语从句的关键是要掌握引导不同状语从句的常用连接词和特殊的连接词即考点。现分别列举如下:1．时间状语从句常用引导词：when,as,while,assoonas,before,after,since,till,until特殊引导词：theminute,themoment,thesecond,everytime,theday，theinstant,immediately,directly,nosooner…than,hardly…when,scarcely…whenIdidn’trealizehowspecialmymotherwasuntilIbecameanadult.WhileJohnwaswatchingTV,hiswifewascooking.Thechildrenranawayfromtheorchard(果园)themomenttheysawtheguard.NosoonerhadIarrivedhomethanitbegantorain.EverytimeIlistentoyouradvice,Igetintotrouble.2．地点状语从句常用引导词：where特殊引导词：wherever,anywhere,everywhereGenerally,airwillbeheavilypollutedwheretherearefactories.Whereveryougo,youshouldworkhard.3．原因状语从句常用引导词：because,since,as,for特殊引导词：seeingthat,nowthat,inthat,consideringthat,giventhat.MyfriendsdislikemebecauseI’mhandsomeandsuccessful.Nowthateverybodyhascome,let’sbeginourconference.Thehigherincometaxisharmfulinthatitmaydiscouragepeoplefromtryingtoearnmore.Consideringthatheisnomorethan12yearsold,hisheightof1.80misquiteremarkable.4．目的状语从句常用引导词：sothat,inorderthat特殊引导词：lest,incase,forfearthat，inthehopethat,forthepurposethat,totheendthatThebossaskedthesecretarytohurryupwiththeletterssothathecouldsignthem.Theteacherraisedhisvoiceonpurposethatthestudentsinthebackcouldhearmoreclearly.5．结果状语从句常用引导词：so…that,so…that,such…that,特殊引导词：suchthat,tothedegreethat,totheextentthat,tosuchadegreethat,Hegotupsoearlythathecaughtthefirstbus.It’ssuchagoodchancethatwemustnotmissit.Tosuchandegreewasheexcitedthathecouldn’tsleeplastnight.6．条件状语从句常用引导词：if,unless,特殊引导词：as/solongas,onlyif,providing/providedthat,supposingthat,incasethat,onconditionthatWe’llstartourprojectifthepresidentagrees.Youwillcertainlysucceedsolongasyoukeepontrying.Providedthatthereisnoopposition,weshallholdthemeetinghere.7．让步状语从句常用引导词：though,although,evenif,eventhough特殊引导词：as(用在让步状语从句中必须要倒装)，while(一般用在句首)，nomatter…，inspiteofthefactthat,while,whatever,whoever,wherever,whenever,however,whicheverMuchasIrespecthim,Ican’tagreetohisproposal.尽管我很尊敬他，我却不同意他的建议。Theoldmanalwaysenjoysswimmingeventhoughtheweatherisrough.Nomatterhowhardhetried,shecouldnotchangehermind.Hewon’tlistenwhateveryoumaysay.8．比较状语从句常用引导词：as(同级比较),than(不同程度的比较)特殊引导词：themore…themore…;justas…，so…;AistoBwhat/asXistoY;no…morethan;notAsomuchasBSheisasbad-temperedashermother.Thehouseisthreetimesasbigasours.Themoreyouexercise,thehealthieryouwillbe.Foodistomenwhatoilistomachine.食物之于人，犹如油之于机器。9．方式状语从句常用引导词：as,asif,how特殊引导词：thewayWheninRome,doastheRomando.Shebehavedasifsheweretheboss.Sometimesweteachourchildrenthewayourparentshavetaughtus.10.状语从句的简化状语从句的省略状语从句同时具备下列两个条件:①主句和从句的主语一致，或从句主语为it；②从句主要动词是be的某种形式。从句中的主语和be动词常可省略。例如：When(themuseumis)completed,themuseumwillbeopentothepublicnextyear.He’llgototheseasideforhisholidayif(itis)possible.另外，比较状语从句经常省略。例如：I’mtallerthanhe(istall).Thehigherthetemperature(is),thegreaterthepressure(is).就状语从句而言,有时为了使语言言简意赅,常常将状语从句进行简化。状语从句的简化现象在口语中较为普遍,而且在高考中的复现率也较高。因此,有必要对其进行全面、透彻的了解。状语从句的简化现象常存在于以下五种状语从句中:①由if,unless等引导的条件状语从句;②由although,though,evenif/though等引导的让步状语从句;③由when,while,as,before,after,until/till等引导的时间状语从句;④由as,asif等引导的方式状语从句;⑤由as,than等引导的比较状语从句。下面针对这五种情形作一归纳。(1)当状语从句的主语是it,且谓语动词是be时,it和be要完全简化掉。例如:If(itis)possible,hewillhelpyououtofthedifficulty.如果可能的话,他会帮你摆脱困境。Youmustattendthemeetingunless(itis)inconvenienttoyou.除非情况对你来说不方便,否则你必须出席这次会议。(2)当状语从句的主语和主句的主语一致时,从句可以将主语和be动词简化掉。常用于以下几种情形:a.连词+形容词As(hewas)young,helearnedhowtorideabike.他小时候就学会了骑自行车。Whenever(sheis)free,sheoftengoesshopping.她有空就去逛商店。Workhardwhen(youare)young,oryou'llregret.少壮不努力,老大徒伤悲。b.连词+名词While(hewas)ayoungboy,hewasalwaysreadytohelpothers.他在孩提时代就乐于助人。Although(hewas)afarmer,nowheisafamousdirector.尽管他曾是个农民,而现在是位著名的导演了。c.连词+现在分词As(shew