冲刺高考英语语法讲解与练习 名词性从句

名词性从句主语从句、表语从句、宾语从句、同位语从句，在整个句子中所起的作用，相当于一个名词。因此，这四种从句通称为名词性从句。引导名词性从句的连接词可分为三类：连接词：that,whether,if（不充当从句的任何成分）连接代词：what,whatever,who,whoever,whom,whose,which.连接副词：when,where,how,why主语从句一、主语从句的概念与类型主语从句在复合句中作主句的主语,引导主语从句的词有从属连词that,whether以及连接代词who,what,which,whoever,whatever,whichever和连接副词when,where,why,how等.例如:Thatshewaschosenmadeusveryhappy.她当选了使我们很高兴.Whatcausedtheaccidentisacompletemystery.是什么导致了这次事故还完全是一个谜.Whethershewillcomeornotisstillaquestion.她是否来还是一个问题.Whichteamwillwinthematchisstillunknown.哪个队会赢得这场比赛还不知道.Whoevercomestothepartywillreceiveapresent.参加聚会的每一个人都将收到一份礼物.Whentheywillstarthasnotbeendecidedyet.他们何时出发还没决定.注意:上述例句中的主语从句都是放在句首,但有时为了使句子结构平衡,避免"头重脚轻",常用it作形式主语,而把从句放在后面.例如:Itisapitythatshehasmadesuchamistake.她犯了这样一个错误,真是遗憾.Itdependsontheclimatewhethertheyaregoingshoppingtoday.他们是否今天去购物还得看天气情况.这样就构成了下面一些常用句型:1)Itis+adj./n.+从句Itisapity/shamethat...遗憾的是……Itispossiblethat...很可能……Itisunlikelythat...不可能……2)It+不及物动词+从句Itseems/appearsthat...似乎……Ithappenedthat...碰巧……3)It+be+过去分词+从句Itissaidthat...据说……Itisknowntoallthat...众所周知……Itisreportedthat...据报道……Itisbelievedthat...据信……;人们相信……Itissuggestedthat...有人建议……Itmustbepointedoutthat...必须指出……Ithasbeenprovedthat...已证明…….例如:Itisbelievedthatatleastascoreofbuildingsweredamagedordestroyed.据信,至少有二十座楼房遭到破坏或彻底毁掉.Itissuggestedthatthemeetingshouldbeputoff.有人建议会议延期召开.It'sreportedthatthreepeoplewerekilledintheaccidentandfivewerehurtbadly.据报道,事故中三人丧生,五人重伤.ItisknowntoallthatTaiwanisaninseparablepartofChina.众所周知,台湾是中国不可分割的一部分.[巩固练习]1.Does_______matterifhecan'tfinishthejobontime?A.thisB.thatC.heD.it2.Itworriedherabit_______herhairwasturninggrey.A.whichB.thatC.ifD.for3._______isafactthatEnglishisbeingacceptedasaninternationallanguage.A.ThereB.ThisC.ThatD.It二、学习主语从句应该注意的几个问题1)引导词that与whatwhat既有引导主语从句的作用,同时又在从句中作句子成分(主语、宾语、表语等).这时what相当于allthat/everythingthat...,常译成"所……的(东西、事情、话等.)";而that只起连接作用,本身无实际意义,在从句中也不担当任何句子成分.但that引导的主语从句放在句首时,不能省略that.例如:Whatisdonecan'tbeundone.(谚语)已成定局,无可挽回.Whatwecan'tgetseemsbetterthanwhatwehave.我们得不到的东西似乎比已得到的要好.Thatweshouldworkoutaplantodealwiththepresentserioussituationisimportant.我们应该制定一项计划来应付目前严峻的形势,这一点非常重要.Thatanewteacherwillcometoteachusgeographyistrue.一位新老师将来教我们地理,这是真的.[巩固练习]4._______whattheytoldmereallytrue?A.HasB.IsC.DoesD.Have5.Itmatterslittle_______amandies,but_______mattersmuchis_______helives.A.how;what;howB.how;it;howC.why;it;whyD.that;what;that6._______shecouldn'tunderstandwas_______fewerandfewerstudentsshowedinterestinherlessons.A.What;whyB.That;whatC.What;becauseD.Why;that7.Itisprettywellunderstood_______controlstheflowofcarbondioxideinandouttheatmospheretoday.A.thatB.whenC.whatD.how8._______fashiondiffersfromcountrytocountrymayreflecttheculturaldifferencesfromoneaspect.A.WhatB.ThatC.ThisD.Which9.-Whatmadeherparentssoangry?-_______shehadfailedintheexamination.A.AsB.BecauseC.SinceD.That2)引导词if和whetherif和whether引导动词后的宾语从句时一般可通用,但介词后的宾语从句、主语从句(放在句首时)、表语从句常由whether引导.例如:Whethershewillgohomeornotisunknown.她是否回家还不得而知.Whetherweshallraiseducksorgeeseremainstobedecided.我们是养鸭还是养鹅仍没决定.=Itremainstobedecidedwhether/ifweshallraiseducksorgeese.但我们不能说Ifweshallraiseducksorgeeseremainstobedecided.[巩固练习]10._______we'llgocampingtomorrowdependsontheweather.A.IfB.WhetherC.ThatD.Where3)其它引导词连接代词who,which,whom,whose有各自的意义,起连接作用,并在从句中充当语、宾语、表语、定语等;连接副词when,where,why,how等有各自的意义,起连接作用,并在从句中充当状语.[巩固练习]11.-Doyouremember_______hecame?-Yes,Ido.Hecamebycar.A.howB.whenC.thatD.if12.Itwasamatterof_______wouldtaketheposition.A.whoB.whoseC.whomD.whomever13.-IdrovetoZhuhaifortheairshowlastweek.-Isthat_______youhadafewdaysoff?A.whyB.whenC.whatD.where14.Ireadaboutitinsomebookorother,doesitmatter_______itwas?A.whereB.whatC.howD.which三、语气在Itisnecessary/natural/important/strange...+that-clause这类句型里,that所引导的主语从句中谓语动词用"should+原形",表虚似语气.例如:Itisnecessarythattheproblemshouldbesettledatonce.这个问题必须马上解决.It'sstrangethatheshouldhavegoneawaywithouttellingus.他竟然没向我们说一声就走了,真是奇怪.[巩固练习]15.Itisnecessarythatacollegestudent_______atleastaforeignlanguage.A.mastersB.shouldmasterC.masteredD.willmaster四、以it作形式主语的主语从句与强调句型的区别"Itbe+adj./n.+that-clause"与强调句型均有Itbe...that...之类的语言标志,但不同的是:①前者中的that从句是主语从句.若删掉其中的Itbe和that,则剩余部分不论结构还是语意都不能成为一个句子;但若将后者中的Itbe和that去掉,则剩余部分的结构和语意仍能构成一个完整的句子.②强调句型译为汉语时可加上"正是……"或"就是……"之类的字眼,而主语从句则不可以.请比较下面两个句子:ItissurprisingthatMaryshouldhavewonfirstplace.令人惊奇的是玛莉竟然获得了第一名.ItisMarythathaswonfirstplace.正是玛莉得了第一名.第一句话中的It是形式主语,that引导的是主语从句.句中的Itis和that无法删除,一旦删除句子就不成立.第二句是强调句型,其中的Itis和that可以去掉,因为没有Itis和that句子仍然很通顺.Key:1-5DBDBA6-10ACBDB11-15AAADB2.宾语从句名词句用作宾语的从句叫宾语从句。引导宾语从句的关联词与引导主语从句表语从句的关联词大致一样，在句中可以作谓语动词或介词及非谓语动词的宾语。1.由连接词that引导的宾语从句由连接词that引导宾语从句时，that在句中不担任任何成分，在口语或非正式的文体中常被省去，但如从句是并列句时,第二个分句前的that不可省。例如：HehastoldmethathewillgotoShanghaitomorrow.他已经告诉我他明天要去上海。Wemustneverthink(that)wearegoodineverythingwhileothersaregoodinnothing.我们决不能认为自己什么都好，别人什么都不好。注意：在demand、order、suggest、decide、insist,desire,demand,request,command等表示要求、命令、建议、决定等意义的动词后，宾语从句常用“（should）+动词原形”。例如：Iinsistthatshe(should)doherworkalone.我坚持要她自己工作。Thecommanderorderedthattroops(should)setoffatonce.司令员命令部队马上出发。2.用who，whom,which,whose,what,when,where,why,how,whoever,whatever,whichever等关联词引导的宾语从句相当于特殊疑问句，应注意句子语序要用陈述语序。例如：Iwanttoknowwhathehastoldyou.我想知道他告诉了你什么。Shealwaysthinksofhowshecanworkwell.她总是在想怎样能把工作做好。Shewillgivewhoeverneedshelpawarmsupport.凡需要帮助的人，她都会给予热情的支持。3.用whether或if引导的宾语从句，其主语和谓语的顺序也不能颠倒，仍保持陈述句语序。此外，whether与if在作“是否”的意思讲时在下列情况下一般只能用whether，不用if：a.引导主语从句并在句首时；b.引导表语从句时；c.引导从句作介词宾语时；d.从句后有“ornot”时；e.后接动词不定式时。例如：Whetherthereislifeonthemoonisaninterestingquestion.月球上有没有生命是个有趣的问题。Thequestioniswhethersheshouldhavealowopinionofthetest?Everythingdependsonwhetherwehaveenoughmoney.一切要看我们是否有足够的钱。Iwonderwhetherhewillcomeornot.我想知道他来还是不来。Canyoutellmewhethertogoortostay?你能否告诉我是去还是留？4.注意宾语从句中的时态呼应，当主句动词是现在时，从句根据自身的句子情况，而使用不同时态。例如：hestudiesEnglisheveryday.（从句用一般现在时）hestudiedEnglishlastterm.（从句用一般过去时）Iknow(that)hewillstudyEnglishnextyear.（从句用一般将来时）hehasstudiedEnglishsince1998.（从句用现在完成时）当主句动词是过去时态（could,would除外），从句则要用相应的过去时态，如一般过去时，过去进行时，过去将来时等；当从句表示的是客观真理，科学原理，自然现象，则从句仍用现在时态。例如：TheteachertoldusthatTomhadleftusforAmerica．5.think,believe,imagine,suppose等等动词引起的否定性宾语从句中，要把上述主句中的动词变为否定式。即将从句中的否定形式移到主句中。例如：Wedon’tthinkyouarehere.我们认为你不在这。Idon’tbelievehewilldoso.我相信他不会这样做。3.表语从句在句中作表语的从句叫表语从句。引导表语从句的关联词与引导主语从句的关联词大致一样，表语从句位于连系动词后，有时用asif引导。其基本结构为：主语+系动词+that从句。（一）表语从句的引导词引导表语从句的词有连词that,whether，连接代词和连接副词，关系代词型what，以及asif,asthough,because等连词。1.由that引导Thefactisthathedoesn’treallytry.事实是他没有做真正的努力。ThetroubleisthatIhavelosthisaddress.麻烦的是我把他的地址丢了。Mysuggestionisthatweshouldtellhim.我的建议是我们应该告诉他。Hissolerequirementwas(is)thatthesystemwork.他唯一的要求是这个制度能起作用。Myideaisthatweshouldstartmakingpreparationsrightnow.我的意见是我们马上就开始做准备工作。2.由whether引导Thequestioniswhetherthefilmisworthseeing.问题是这部电影是否值得看。【注意】whether可引导表语从句，但与之同义的if却通常不用于引导表语从句。3.由连接代词引导YouarenotwhoIthoughtyouwere.你已不是我过去所想像的人。Theproblemiswhowecangettoreplaceher.问题是我们能找到谁去替换她呢。Thequestioniswho(m)weshouldtrust.问题是我们应当相信谁。WhatIwanttoknowiswhichroadweshouldtake.我想知道的是我们应走哪条路。4.由连接副词引导Theproblemishowwecanfindhim.问题是我们如何找到他。ThatwaswhenIwasfifteen.这是我15岁时发生的事。That’swhereIfirstmether.那就是我第一次遇见她的地方。That’swhyhedidn’tcome.这就是他没有来的缘故。That’swhyIobjecttotheplan.这就是我反对这个计划的原因。That’swhereyouarewrong.这就是你不对的地方。5.由关系代词型what引导That’swhatIwanttostress.这是我想强调的。That’swhatweareherefor.我们来这里就为了这个。Fameandpersonalgainiswhatthey’reafter.他们追求的是名利。Heisnolongerwhathewas.他已经不是以前的他了。6.由asif/asthough引导Itisn’tasifyouweregoingawayforever.又不是你离开不回来了。NowitwasasthoughshehadknownMillieforyears.现在好像她认识米莉已有好多年了似的。Itisnotasthoughwewerepoor.又不是我们家里穷。7.由because引导ItisbecauseIloveyoutoomuch.那是因为我太爱你了。That’sbecauseyoucan’tappreciatemusic.这是因为你不能欣赏音乐。IfI’mabitsleepy,it’sbecauseIwasupallnight.如果我有点困，是因为一夜没睡。It'sbecauseIpassedaslipofpaperforJohntoHeleninclass.这是因为我在上课中替约翰传纸条给海伦。【注意】because可引导表语从句，但与之同义的since,as,for等也不用于引导表语从句。（二）、连词that的省略问题引导表语从句的that通常不省略，但在口语或非正式文体中有时也可省略：Myideais(that)weshoulddoitrightaway.我的意见是我们应该马上干。Thetroubleis(that)heisill.糟糕的是他病了。4.同位语从句同位语从句说明其前面的名词的具体内容。同位语从句通常由that引导，可用于同位语从句的名词有advice、demand、doubt、fact、hope、idea、information、message、news、order、problem、promise、question、request、suggestion、truth、wish、word等。）一）、同位语从句的引导词引导同位语从句的词语通常有连词that，whether，连接代词和连接副词等。1.由that引导Weheardthenewsthatourteamhadwon.我们听到消息说我们队赢了。Theywereworriedoverthefactthatyouweresick.他们为你生病发愁。Thenewsthatwearehavingaholidaytomorrowisnottrue.明天放假的消息不实。I’vecometotheconclusionthatitwasunwisetodothat.我得出结论这样做是不明智的。Thefactthatthemoneyhasgonedoesnotmeanitwasstolen.那笔钱不见了这一事实并不意味着是被偷了。HereferredtoCopernicus’statementthattheearthmovesroundthesun.他提到了哥白尼关于地球绕太阳转的说法。【注意1】在某些名词(如demand,wish,suggestion,resolution等)后面的同位语从句要用虚拟语气。如：Theywerefacedwiththedemandthatthistaxbeabolished.他们面对废除这个税的要求。Theyexpressedthewishthatsheaccepttheaward.他们表示希望她接受这笔奖金。TherewasasuggestionthatBrownshouldbedroppedfromtheteam.有一项建议是布朗应该离队。Thesuggestionthatthenewrulebeadoptedcamefromthechairman.采纳新规则的建议是主席提出的。Theresolutionthatwomenbeallowedtojointhesocietywascarried.允许妇女参加这个协会的决议通过了。Icanunderstandtheireagernessthatyoushouldbethemainspeaker.我理解他们希望你作主要发言人的殷切心情。【注意2】引导同位语从句的连词that通常不省略，但在非正式文体中也可以省去。如：HegabbedhissuitcaseandgavetheimpressionhewasboardingtheTokyoplane.他拿起了手提箱，给人的印象是他要登上飞往东京的飞机了。2.由whether引导Thereissomedoubtwhetherhewillcome.他是否会来还不一定。Answermyquestionwhetheryouarecoming.你回答我的问题：你来不来。Thequestionwhetheritisrightorwrongdependsontheresult.这个是对还是错要看结果。Wearenotinvestigatingthequestionwhetherheistrustworthy.我们不是在调查他是否可以信任的问题。【注意】whether可引导同位语从句，但if不能引导同位语从句。3.由连接代词引导Haveyouanyideawhattimeitstarts?你知道什么时候开始吗?From1985-90Iwasaninstructorattheregionalpartyheadquarters.AfterthatIwentbacktoworkinafactory.ThenIhadnoideawhatacasinowas.从1985年到1990年我是地方党部的教员。随后我回到一家工厂工作。当时我不知道赌场是什么样的地方。4.由连接副词引导Ihavenoideawhenhewillcomeback.我不知道他什么时候回来。Itisaquestionhowhedidit.那是一个他如何做的问题。Hehadnoideawhysheleft.他不知道她为什么离开。YouhavenoideahowworriedIwas!你不知道我多着急!（二）、关于分离同位语从句有时同位语从句可以和同位的名词分开。如：Thestorygoesthathebeatshiswife.传说他打老婆。Thenewsgotaboutthathehadwonacarinthelottery.消息传开说他中彩得了一辆汽车。Therumourspreadthatanewschoolwouldbebuilthere.谣传这里要盖一所新学校。ReporthasitthattheSmithsareleavingtown.有传言说史密斯一家要离开这座城市。Thethoughtcametohimthatmaybetheenemyhadfledthecity.他想到可能敌人已逃离这座城市。Theordersooncamethatallcitizensshouldevacuatethevillage.不久命令下来，所有居民都必须撤出村子。(二.名词性从句中的虚拟语气1.主语从句中的虚拟语气主语从句中的虚拟语气主要取决于某些形容词和过去分词，用来表示建议、命令、要求、惊异和失望等。其形式为：（should）+动词原形。常这样用的形容词有：appropriate适当的advisable适当的，合理的better较好的desirable理想的essential精华的imperative迫切的important重要的insistent坚持的natural自然的necessary必要的preferable优越的，较好的strange奇怪的urgent紧迫的vital极其重要的过去分词有：desired,demanded,ordered,requested,suggested,recommended,required等。例如：Itisessentialthatyou(should)winthevoters’hearts.赢得选民的心是绝对必要的。Itwassuggestedthathe(should)jointheclubactivities.有人提议他应该参加俱乐部的活动。2.表语从句和同位语从句中的虚拟语气在表示建议、命令、主张、目的和愿望等名词后面的表语从句和同位语从句中谓语动词要求使用虚拟语气。其形式为：（should）+动词原形。常这样用的名词有：resolution决心，决议pray恳求decision决议motion提议suggestion建议preference选择proposal提议advice劝告recommendation推荐desire愿望demand要求requirement要求order命令necessity必要性request要求idea主意、想法例如：Hegaveordersthattheguests(should)behospitablyentertained.他下令热情款待这些客人。Hisproposalisthatwe(should)getridofthebadhabits.他提议我们应该摈弃这些不良习性。3.宾语从句中的虚拟语气1）某些动词后所接宾语从句中的谓语动词要求用虚拟语气，用来表示建议、命令和要求等。其形式为：（should）+动词原形。常这样用的动词有：ask要求advise劝告determine决定decide决定command命令insist坚持intend打算move提议prefer宁愿propose提议order命令recommend推荐request要求require要求suggest建议urge主张demand要求desire渴望direct命令例如：Heinsistedthatthemeetingbeputoff.他要求推迟那个会议。Theyproposedthatalltheplansshouldbediscussedatthemeeting.他们建议所有的计划都应该在会上讨论。2）在以it为形式宾语的复合宾语从句中也可以用虚拟语气，其形式为：（should）+动词原形。这一句型中使用的形容词（宾补）与主语从句中的虚拟语气所使用的形容词相同。例如：Wethinkitadvisablethathe(should)thinkdeeplybeforeacting.我们认为他在行动之前好好考虑一下才是明智的。3）wish后面所跟的宾语从句中的虚拟语气表示某种不能实现的愿望。其主要形式有三种：表示对现在情况的虚拟：wish+主语+动词过去式或were表示对过去情况的虚拟：wish+主语+had+过去分词表示对将来情况的虚拟：wish+主语+would+动词原形。例如：IwishIknewwhatwasgoingtohappen.但愿我能知道要发生什么事。Shewishedshehadstayedathome.她懊悔的是她当时要是在家就好了。IwishIwererich.我恨不得我很有钱。注意：在表示对过去情况的虚拟时，有时也可以用下列形式：wish+主语+would（could）+have+过去分词IwishIcouldhaveseenherlastnight.要是我昨天晚上能够见到她那该多好。4.if条件句中的虚拟语气形式1）if非真实条件句所表示的假设则是不可能或不大可能发生或实现的，句中的主句与从句都用虚拟语气。在if非真实虚拟条件句中，主句和从句谓语动词主要有下面几种形式：假设类型条件从句谓语动词形式主句谓语动词形式与现在事实相反动词过去时（be用were）Should（would，could，might）+动词原形与过去事实相反Had+过去分词Should（would，could,might）+have+过去分词与将来事实可能相反动词过去时（should+动词原形，wereto+动词原形）Should（would，could，might）+动词原形Iftherewerenogravity,weshouldnotbeabletowalk.假如没有引力，我们就不可能行走。Iwouldn’thaveknownwhatthesewereforifIhadn’tbeentold.假如别人不告诉我，我就不知道这些东西是干什么的了。2）正式文体中，有时可把虚拟条件句中的连词if省去，而将were，had,should等助动词（不包括行为动词）提到主语前面。如果句中没有were，had或should时，既不能省略if，也不能倒装。例如：WereItomeethimtomorrow(=IfIweretomethimtomorrow),Ishouldaskhimaboutit.要是我明天见到他，我就会问他这件事的。HadIhadthemoneylastyear(=IfIhadhadthemoneylastyear),Iwouldhaveboughtthehouse.如果我去年有了这笔钱，我就买那所房子了。Shouldtherebeanytroublewiththeboiler,theautomaticcontrollingunitwouldcutoffthefueloilsupply.假如锅炉出问题的话，自控装置会自动切断燃油的供给。3）通常情况下，在非真实条件句中主句和从句的谓语动词所指时间是一致的，但有时也可能指不同的时间，这时要根据上下文的意思采用不同的谓语动词形式。例如：IfIwereyou,Iwouldhavetakenhisadvice.我要是你，我就采纳了他的建议。（从句指现在，主句指过去）Iftheweatherhadbeenmorefavorable,thecropwouldbegrowingstillbetter.如果气候更适宜一些，庄稼会长得更好。（从句指过去，主句指现在）5.含蓄虚拟条件句1）有时假设的情况并不以条件从句形式表示出来，而是通过一个介词短语或其他方式表示。常用的词或短语有：without,butfor,butthat,otherwise,or,but等。例如：Withoutyourhelp(=Ifwehadnothadyourhelp),wecouldnothavesucceeded.要是没有你的帮助，我们就不会成功的。Butforelectricity(=Iftherewerenoelectricity),therewouldbenomodernindustry.要是没有电，就不会有现代工业。Hewashavingameeting;otherwisehewouldhavecomeovertohelpus.他当时正与他的学生进行讨论，否则的话他就来帮我们了。Hefeltverytiredyesterday,orhewouldhaveattendedtheparty.他昨天很累，不然他就参加那个聚会了。2）在某些暗含虚拟条件的简单句中，虚拟语气可通过上下文表现出来。谓语动词用should/wouldbe形式和should/wouldhavebeen虚拟形式。例如：Anymeninhispositionwouldhavedonelikethat.任何人处在他的位置都会那么做的。Youshould(oughtto)havecomeearlier.你本应来得早点。6.其他句型中的虚拟语气1）在wouldrather,wouldsooner,wouldjustassoon,mightaswell和wouldprefer等后面所跟的从句中，也可以用虚拟语气，表示愿望，意为“宁愿、但愿”。其形式为：①“wouldrather(wouldsooner…)+主语+谓语动词过去式”表示现在或将来的情况。②“wouldrather(wouldsooner)+主语+动词过去完成式”表示过去的情况。例如：I’dratherhedidn’tgonow.要是他现在不走就好了I’djustassoonyouhadbeenhereyesterday.要是你昨天在这里就好了。2）在句型“Itis(high/about)time…”后面也可以跟虚拟语气，从句中常用过去式。有时也用“（should）+动词原形”，意为“该是……的时候了”。例如：Itistimethattheboy(should)gotoschool.这个小孩该上学了。Itishightime(that)theweatherimproved.天气真该好起来了。3）在“ifonly”引起的感叹句中也要求用虚拟语气，表示愿望。形式为：①用过去时或“would/could+动词原形”表示与现在或未来事实相反的愿望。②过去完成时表示与过去事实相反的愿望。例如：Ifonlyyouwouldlistentoouradvice.要是你听我们的建议就好了。IfonlyIhadnotbeenbusylastweek!要是上周我不忙该多好啊！Ifonlyshecouldmarryme.但愿她能嫁给我。注：ifonly也可以用于虚拟条件句中。例如：IfonlyIhadmoremoney,Icouldbuyacar.要是我有更多的钱，我就可以买辆车了。4）连接词“incase,lest,forfearthat”可以用来引导虚拟语气。其形式通常为：“…lest(incase,forfearthat)+主语+should+动词原形”。Lest,forfearthat句中的should可以省去，incase句中的should通常不省去，但是incase句中可以不用虚拟语气，而用陈述语气。Lest,forfearthat后面也可以接其他形式。例如：Hetookhiscoatwithhimincaseitshouldrain.他带着雨衣以防下雨。IwillnotmakeanoiseforfearthatI(should/might)disturbyou.我不会做声的，以免打扰你。Caremustbetakeninusingthismethodlestoverflow(should)occur.在使用这以方法的时候要谨慎小心，以免发生溢流现象。同位语从句与定语从句的区别1．意义的不同同位语从句是用于说明所修饰名词的具体内容的，它与被修饰词语通常可以划等号；而定语从句是限制所修饰名词的，它的作用是将所修饰的名词与其他类似的东西区别开来：Wearegladatthenewsthathewillcome.听到他要来这个消息我们很高兴。(news的内容就是thathewillcome，故that引导的是同位语从句)Wearegladatthenewsthathetoldus.听到他告诉我们的这个消息我们很高兴。(that从句是限制thenews的内容的，即我们高兴只是因为他告诉的这个news而不是其他的news，故that从句为定语从句)2.引导词的不同what,how,if,whatever等可引导名词性从句，但不引导定语从句。3.引导词的功能上的不同that引导同位语从句时，它不充当句子成分，而引导定语从句时，它作为关系代词，要么充当定语从句的主语，要么充当定语从句的宾语。如上例thathetoldus中的that就充当told的宾语。4.被修饰词语的区别同位语从句所修饰的名词比较有限，通常有hope,wish,idea,news,fact,promise,opinion,suggestion,truth等，而定语从句所修饰的名词则非常广泛。另外，when和where引导定语从句时，通常只修饰表示时间和地点的名词，而它们引导同位语从句时却不一定；又如why引导定语从句，它通常只修饰名词thereason，而它引导同位语从句时则不一定：Ihavenoideawhentheywillcome.我不知道他们什么时候来。(同位语从句)I’llneverforgetthedayswhenIlivedthere..我永远不会忘记我住在那儿的日子。(定语从句)Wedon’tunderstandtheproblemwhythisisthebestchoice.我们不明白这个问题，为什么这是最好的选择。(同位语从句)Thereasonwhyhedidn’tcometothemeetingisthatheisill.他未能来开会，原因是他生病了。(定语从句)Theprimaryreasonwasskepticismthatarailroadbuiltthroughsochallengingandthinlysettledastretchofdesert,mountain,andsemiaridplaincouldpayaprofit.同位语从句主句:Theprimaryreasonwasskepticism.that从句做skepticism的同位语，具体说明skepticism.that从句主干arailroadcouldpayaprofit.其他的都是用来修饰railroad...过去分词短语做后置定语修饰railroad.常见的同位语从句先行词是news，idea，fact，promise，question，doubt，thought，hope，message，suggestion，words（消息），possibility等。这些都是抽象名词，你的这个例子中skepticism,怀疑态度也是抽象名词。同位语从句的特点是，你可以去掉先行词，句子仍然成立，没有语法错误。这里Theprimaryreasonwasthatarailroadbuiltthroughsochallengingandthinlysettledastretchofdesert,mountain,andsemiaridplaincouldpayaprofit.无错误。所以原句是同位语从句。名词性从句专项练习100题1.Hissuccesswasbecauseof________hehadbeenworkinghard.A.thatB.thefactwhichC.thefactthatD.thefact2.“IsMaryfromNewYorkCity”“Idon'tknow_______.”A.fromwhatcitydoesshecomefromB.fromwhatcityshecomeC.whatcitydoesshecomefromD.whatcityshecomesfrom3.________makesmistakesmustcorrectthem.A.WhatB.ThatC.WhoeverD.Whatever4.ThereasonwhyIdidn'tgotoShanghaiwas________anewjob.A.becauseIgotB.becauseofgettingC.IgotD.thatIgot5.Itworriedherabit____herhairwasturninggrey.A.whileB.thatC.ifD.for6.Henrykilledthedog.I'llaskhimwhy________.A.didhedothatB.hedidthatC.hedidD.hehasdoneso7.HaveyouseenHenrylatelyMybosswantstoknow________.A.howheisgettingalongB.howishegettingalongC.whatheisgettingalongD.whatishegettingalong8.Itisgenerallyconsideredunwisetogiveachild____heorshewants.A.howeverB.whateverC.whicheverD.whenever9.Heaskedme________withme.A.whatisthetroubleB.whatwrongwasC.whatwasthematterD.whattroubleitis10.Iamsure________hesaidistrue.A.thatB.aboutthatC.ofthatD.thatwhat11.Whenandwhyhecamehere________yet.A.isnotknownB.arenotknownC.hasnotknownD.havenotbee12.Iwonderhowmuch________.A.doesthewatchcostB.didthewatchcostC.thewatchcostedD.thewatchcosts13.Maryis________someonemightrecognizeher.A.afraidofB.afraidaboutC.afraidthatD.afraidfor14.________isnoreasonfordismissingher.A.BecauseshewasafewminuteslateB.OwingtoafewminuteslateC.ThefactthatshewasafewminuteslateD.Beingafewminuteslate15.Theycametotheconclusion________byacomputer.A.thatnotallthingscanbedoneB.becauseofnotallthingsbedoneC.beingnotallthingscanbedoneD.becausenotallthingscanbedone16.Whytheexplosionoccurredwas________thelaboratoryattendanthadbeencareless.A.forB.becauseC.sinceD.that17.Idon'tdoubt________he'llcome.A.thatB.ifC.whatD.whether18.—“Whydidyougotothewrongclass,Mr.Wang”—“Well,Iforget_______Iwassupposedtogoto.”A.whichtheroomB.whichroomC.whatwastheroomD.whatroomwasit19.Outputisnowsixtimes________itwasbeforeliberation.A.thatB.whichC.whatD.ofwhich20.Mary:Helenisamerewasherwoman,yetshe'snowbuyingabighouse.Carol:Yes.Becauseshe'salwayssaved________.A.whatlittlesheearnsB.howlittlesheearnsC.forlittlesheearnsD.withlittlesheearns21.______surprisedmemostwas______suchalittleboyofsevencouldplaytheviolinsowell.A.That…whatB.What…thatC.That…whichD.What…which22.Wegavehim________helpwecould.A.whichB.whatC.thatD.this23.Sheispleasedwithwhatyouhavegivenhimand________youhavetoldhim.A.thatB.whichC.allwhatD.allthat24.Excusemewouldyoupleasetellme________A.whenthesportsmeetistakenplaceB.whenisthesportsmeetgoingtobeheldC.whenisthesportsmeettobeginD.whenthesportsmeetistotakeplace25.Doyouhappentoknow________A.whatsizeshoeshewearsB.howbigshoeshewearsC.whatisthesizeofhisshoesD.whatnumbershoesarehis26.Thisbookwillshowyou________canbeusedinothercontexts.A.howyouhaveobservedB.howwhatyouhaveobservedC.thatyouhaveobservedD.howthatyouhaveobserved27.Wheredoyouthink________A.hashegoneB.hashebeenC.he'sgoneD.washe28.Doyouknow________A.howmanypopulationsthereareintheworldB.howmuchpopulationthereisintheworldC.howmanythepopulationoftheworldisD.whatthepopulationoftheworldis29.Wouldyougoandsee________outsideA.whattotakeplaceB.whatTomhashappenedC.whatishappeningD.whatthematterhadbeen30.Thesubjectof"WhatisinterestingisthatIdonotevenknowhim."is_______.A.whatB.interestingC.WhatisinterestingD.I31.________IthinkheisCharles.A.WhodoyouthinkheisB.DoyouthinkwhoheisC.WhomdoyouthinkheisD.Doyouthinkwhoheis32.Hedidn'tknowwhichroom________.A.theylivedB.theylivedinC.didtheyliveD.didtheylivein33.Thelittleboyate________hismothergavehim.A.thatB.whichC.whateverD.nomatterwhat34.Thecityisnolonger________.A.whatitisB.thatitusedtobeC.whichitwasD.whatitusedtobe35.Myparentsused________theyhadtogetanewcarforme.A.whichB.thatC.whatD.allwhat36.________wegoswimmingeveryday________usalotofgood.A.If…doB.That…doC.If…doesD.That…does37.________wastheidea_______thewifethoughtofA.What…thatB.That…whatC.How…whyD.Why…how38._______didhetellhiswife________hewishedtodoA.That…whatB.What…thatC.Where…whichD.Which…where39.Oneofthemenheldtheview________thebooksaidwasright.A.whatthatB.thatwhatC.thatwhichD.whichthat40.Ihavenoidea________ornothehasfinishedthework.A.ifB.thatC.whetherD.which41.—“Doyouknow________”—“Hisfatherisadoctor.”A.whatishisfatherB.whoishisfatherC.whathisfatherisD.whohisfatheris42.Isthis________wemeteachothertwoyearsagoA.placeB.placeinwhichC.whereD.placewhich43.It________Bobdrivesbadly.A.thinksthatB.isthoughtwhatC.thoughtthatD.isthoughtthat44.Weallknowthetruth________thereareair,waterandsunlighttherearelivingthings.A.whereB.whereverC.thatD.thatwherever45.Theydiscussed________theycouldsettletheproblemwithoutothers'help.A.ifB.thatC.whatD.whether46.Sheasked________.A.whatIwasdoingwhensherangmeupB.whatwasIdoingwhensherangmeupC.whensherangmeupwhatIwasdoingD.whendidsheringmeupwhatIwasdoing47.—MayIborrowthering—Youcantake_______youlike.A.nomatterwhatB.whichC.whicheverD.that48.Hesaidthathewasfondof________.A.whatbeautifulisB.whatisbeautifulC.beautifuliswhatD.whatitisbeautiful49.Heinsistedthathe________ingoodhealthand_______toworkthere.A.was,besentB.is,is