三大从句语法

从句可分为三类:即名词性从句、形容词性从句（即定语从句）和副词性从(即状语从句）。引导从句的词称作关联句。一、名词性从句引导这些名词性从句的关联词包括：从属连词：that，if,whether连接代词：who,whoeverwhom,whomever，which,whichever，what,whatever，whose连接副词where,when,why,how。其中,从属连词只起连接作用，在从句中不充当任何句法成分，而连接代词和连接副词既起连接作用,在从句中又充当一定的成分。不可省略的连词介词后的连词 2。引导主语从句和同位语从句的连词不可省略。Thatshewaschosenmadeusveryhappy。Weheardthenewsthatourteamhadwon。whether与if均为whether不能被if:。whether引导主语从句并在句首。引导表语从句3.whether4."or例：Whetherhewillcomeisnot。Thefactisthathedidn'tgotothedinner。Idon'tknowifhewillattendthemeeting。,it置于句末。That—从句作主语通常用it作先行词，而将that—从句置于句末，例如：Itisquiteclearthatthewholeprojectisdoomedtofailure。很清楚，整个计划注定要失败。It’sapitythatyoushouldhavetoleave.你非走不可真是件憾事.用it作形式主语的that—从句有以下四种不同的搭配关系:AIt+be+形容+that—从句例:Itisnecessarythat…有必…… Itisimportantthat…重要的…… Itisobviousthat…很明……B.It+be+—ed分+that-从句 例如isbelieved人们相…… Itisknowntoallthat…从所周…… Ithasbeendecidedthat…已决……C。It+be+名+that—从句 例:Itiscommonknowledgethat………是常识 Itisasurprisethat…令人惊奇的…… Itisafactthat…事实……D.It+不及物动+that—分句 例：Itappearsthat…似…… Ithappensthat…巧…… Itoccurredtomethat…我突然想……为保持句子平衡，that引导的宾语从句也常用it句末。这常常出现在主句有形容词或分词作宾语补足语的情况下。Hemadeitquiteclearthathepreferredtolivehere。从属连词whether和if都作是…"解,但if不可引导主语从句和表语从句whether可与or(not）连,而if不可. Idon'tknowwhethersheisathome.Whethershecomesornotmakesnodifference。4。thatwhat引导名词性从句的区别：that,what,.that,what.Healwaysmeanswhathesays. Shesuggested(that)hedoitatonce.5.同位语从句大多由从属连词that引导，常跟在下列名词后面，如fact,idea，opinion，news，hope，belief等，that不可省。同位语从句一般用来解释说明这些名词的具体含义和内容。Wearefamiliarwiththeideathatallmatterconsistsofatoms.Thenewsthatweareinvitedtotheconferenceisveryencouraging.二、形容词性从句引导定语从句的关联词包括：(1)关系代词which,whose,who,as; 关系副:when，where，why.关系代词和关系副词在定语从句中都充当一定的句法成分,关系代词在句中充当动词的宾语时，一般可省去。关系代词的选用比较复杂，它受下列条件的制约: (1）先行词是指还是指物(2）关系代词在从句中的句法功能(3）定语从句是限定性的还是非限定性的。关系代词的选用情况见下表：先行词在从句中的句法功能用于限定性或非限定性定语从句只用于限定性定语从指人或指物 指人指物主语 who which that宾语 whomwhich that定语 whosewhose(ofwhich)Iknowthatheisamanwho（that)meanswhatbesays.Thegentlemanwhom（that)shemetaddressedherwithcourtesy(礼貌).Thewatchwhich（that)waslosthasbeenfound。Hereisthemeterialwhich（that)youneed.You'retheonlyonewhoseadvicehemightlistento.time,day等，则用place,housearea等,则用wherereason。例：I'llneverforgetthemountainvillagewhere(inIspentmychildhood.Idon’tknowthereasonwhy(forwhich）hedidthat.1。当先行词是allsomethingnothing;或先行词前有few，much,some，any,no等修饰时；或先行词前有形容词最高级修时，一般只用that而不用whichexplainedeverything（that)Icanto。Thisisthemostbeautifulcompus（that）I'veeverbeento。定语从句分为限定性定语从句和非限定性定语从句，限定性定语从句与主句关系紧密,,,,句一般不用that引导。引导非限定性定语从句的关系词不可省略。Hisspeech,whichboredeveryone,wentonandon.Thegeneral’sdaughter,whosenameisAnn，gavemeasweetsmile..,一般用which或aswhich在从句中可,aswhichaswhich,as,,又可置于句首。Waterconsistsofhydrogenandwhich(as）isknownto。Ashadbeenexpected，hefinishedfirstindecathlon（十项全能)atthatOlympicGames。4,词+which+whom,+that,则thatwhichthat.Thisistheringonwhichshespent1，000dollars.Oneofmycolleagueswhom(that)youarefamiliarwithwillcometoday.区分关系代词与关系副词方法一：用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词；而不及物动词则要求用关系副词。例如：ThisisthemountainvillagewhereIstayedlastyear.I’llneverforgetthedayswhenIworkedtogetherwithyou方法二：准确判断先行词在定语从句中的成分(主、谓、宾、定、状），也能正确选择出关系代词/关系副词。例1.Isthismuseum_Dyouvisitedafewdaysage?A。whereB.thatC.onwhichD。theone例2.IsthisthemuseumAtheexhibitionwasheld A.wherethatC.onwhichtheone三、副词性从句在复合句中,起状语作用的从句称作状语从句。状语从句分为:时间状语从句、地点状语从句、条件状误从句、原因状语从句、让步状语从句、比较状语从句、目的状语从句、结果状语从句、方式状语从句。状语从句可放在句首或句末.如状语从句位于主语前,一般用逗号将其与主句隔开。（一)时间状语从句Whenyoucrossamainroad，youmustbeverycareful.Untilwelearnthefacts，wecan’tdoanythingaboutit。1。when，as，while引导时间状语从句时都可以表示主句的动作与从句的动作同时发as引导的状语从句中的动作只能是延续的动作或状态.,一般用while,而不用whenas发展、变化的情况时，一般用as，作“…”解。Whenshe，Ishalltellhertowaitforyou. Asshegotolder,shegotWhilePeterwasreadinghiswifewascooking。2。有些副词和一些表示时间的名词词组也可用作从属连词，引导时间状语从句。如instantly，immediately，directly，theday,everytime,theminute，thesecond,themoment等。Immediatelyhearrived,hestarteddescribinguswhathadhappened.Thedayhereturnedhome,hisgrandpawasalradydead.（二)条件状语从句引导条件状语从句的从属连词有：if，unless,as(so)longas,onlyif（只要)。Ifyoudon'tcomeontime，we'llstartoutwithoutyou.As(so）longasyoukeepontrying，you'llcertainlysucceed。注:除了以上提到的从属连词外，还有其它的一些词或词组也可引导条件状语从句。如：providingthat，provided,，supposingthat，，supposethat,，onconditionthat,，incase等。Iwillgoprovidingthatmyexpensesarepaid。要是我的费用有人代付我就去Supposingheisnotathome，whatthen？假如他不在家，那怎么办?Youcanusethebicycleonconditionthatyoureturnittomorrow。只要你明天归还,自行车你可以拿去用.Incaseshecomesback，letmeknowimmediately。假使她回来了,立刻告诉我Taketheraincoatincaseitrains.带着雨衣,以防下雨。（三)原因状语从句:becasue,as,inthat,consideringthat等。Consideringhe’sonlybeenlearningEnglishayearhespeaksitverywell。考虑到他只学了一年英语，他讲得算是很流利了。Wedidn’tknowwhattodoaswewerejustvisitingthere。我们不知道该怎么办，因为当时我们仅仅在那里作访问。Sinceitissohot，let'sgoswimming。既然天气这么热,我们去游泳吧。注that和的用: inthat引导的从句对主句进行解释和说明意思是：在…方面,在于…；因为。now（that)表示既然。Theoryisvaluableinthatitcanprovideadirectionforpractice.理论所以有价值,就在于它能给实践指出方向。Now(that）theweatherhasimproved,let'sgooutforapicnic.既然天气已转好，我们就出去野餐吧.(四）让步状语从句引导让步状语从句的从属连词有： though,although,evenif(eventhough)，as, nomatter…despitethefactthat，inspiteofthefactthat,while。Tiredashewas，hesatuplate。他虽然疲倦,可仍然很晚才睡。Nomatterhowtheyslanderus,wewillnevergivein.不管他们怎样诽谤我们，我们决不让步。WhileIlikethecolorofthehat,Idonotlikeitsshape.虽然我喜欢这顶帽子的颜色,但我不喜欢它的形状。ever后,相当于nomatter+词包括:whatever,，whenever,whoever，however。Whateverhesays,don'tbelevehim.不管他说什么都不要想相信他。Whoeveryouare,youmustobeythetrafficregulations。(五）目的状语从句引导目的状语从句的从属连词有：sothat,inorder，lest，incase,forfear。Theyclimbedtothetopofthebuildinginorderthattheycouldgetaviewofthecity.AskhertohurryupwiththeseletterssothatIcansignthem.Takeanumbrellaincaseitrains。Wedarenotplayjokesonhimlestheshouldbecomeangry。我们不敢开他玩笑生怕他动气。注:sothat和inorderthat的区别：sothat更常用，inorderthat更正式.sothat引导的从句一般置于句末，而inorderthat引导的从句既可置于句首,又可置于句末。Inorderthatthegrassandflowerscouldbloomagain,itwasnecessarythattherocksshould