名词性从句精讲.doc

名词性从句精讲一、概述：起名词作用的从句叫名词性从句。它和名词一样，在句中可充当主语，表语，宾语和同位语。名词从句包括主语从句，表语从句，宾语从句和同位语从句。 名词从句的引导词通常有词形词义在从句中所作成分说明（连接）连词that不作成分也无词义有时可省略 whether, if是否两个有词义但不作成分（连接）代词who(ever)（无论）谁（主格）主语、表语五对不是疑问词，故不存在疑问句式whom(ever)（无论）谁（宾格）宾语whose(ever)（无论）谁（所有格）定语which(ever) （无论）哪个主语、宾语、定语what(ever)（无论）什么主语、宾语、表语、定语（连接）副词when什么时候状语四个不是疑问词，故不存在疑问句式。选词规则由句中语境决定where在哪里状语how怎么、怎样、多么状语why为什么状语注：1、because,as,as if ,as though也可以引导表语从句。2、连接代词与连接副词在从句充当句子成分，连接词whether 和if（是否），as if（好象）在从句中不充当句子成分，只起连接作用。根据句义，如果连接代词与连接副词，whether、if 和as if都用不上时，才用that作连接词（that本身无任何含义）。3、连接代词与连接副词在句中不再是疑问句，因而从句中谓语不用疑问式。4、Wh-从句的语法功能除了和that-从句一样外，还可充当介词宾语、宾语补语和间接宾语等。5、一般说来，what/who等含特指意义，而whatever/whoever等含泛指意义，意为“无论什么/无论谁”。1、名词性从句中连接词的运用名词性从句中的连接词有连词that / whether / as if，连接代词what / who/ which / whose / whatever / whoever / whomever / whichever，连接副词where / when / why / how / wherever / whenever。（1）that的用法。主语从句、表语从句、同位语从句中用that但不能省略。如：That they are good at English is known to us all.The problem is that we dont have enough money.She expressed the hope that they would come to China one day.宾语从句中的连接词that有时可省有时又不可省，在以下几种情况中that不能省略：（A）当that从句和主句谓语动词之间有插入词语或者从句主语之间有插入语时，that不可省略；（B）当that 从句与另一名词性从句并列作宾语时，that不能省，否则成带并列句了的从句了（一般是and连接）（C）当that作介词宾语时，that不可省掉。（D）如果宾语从句本身含有主从复合句时，that一般不宜省。（E）当主、从句之间有时间等状语修饰时，that不宜省略，否则会产生歧义。（F）宾语从句提前时，that不宜省略。（G）简单回答中的宾语从句，that不宜省略。（H）当it作形式宾语代替that引导的宾语从句时，一般保留that为好。Everyone knew what happened and that she was worried. The reason lies in that she works harder than the others do.that从句作主语和宾语时，可以用it 来替换成以下几种结构表达。（在后面“分述”中会讲到，这里略）that和what的区别。that 引导名词性从句时，在主从句中不以当任何句子成分，也没有任何含义；而what引导名词性从句时，在主从句中都要充当一定的句子成分（主、宾、定），what相当于定语从句中的：先行词 + 关系代词（that或which）;即常说的先行词 + that。如：Its shame that he has made such a mistake. Do what he says.同位语从句与定语从句中that的区别。同位语从句中的连词that只起连接作用，在从句中不担当任何句子成分；而定语从句中的关系代词that在句中做宾语或主语，宾语与先行词有修饰关系。如果句子是同位语从句，就应用连词that而不能用which.同位语从句一般放在表具体含义的名词后解释名词的含义或内容，如以下名词：news、fact、suggestion、truth、plan、belief、doubt、possibility、idea等，而定语从句只是对先行词的限定和修饰。如：They expressed the hope that they would come to visit China again.(同位语从句)The hope she expressed is that they would come to visit China again.（定语从句） （2）whether和if的用法。（“是否”，不担任成分也不能省略）whether和if在宾语从句中可以互换，但是作介词宾语时连接词一般用whether。如：It all depends on whether they will come back.但在discuss,consider,decide等动词后引导宾语从句，只能用whether。后面直接跟or not 时用whether。还有whether常与or 连用表示一种选择，if不能这样用； I didnt know whether or not he had arrived in Wuhan. The question of whether they are male or female is not important.主语从句置句首、介词宾语、表语从句、同位语从句中只能用whether。不用if。（当主语从句用了形式主语it时，则可用if引导！）如： Whether the meeting will be put off has not been decided yet. We ought to discuss carefully the question whether we can do it or not.同位语。whether也可与动词不定式连用但if不能。如：I have not decided whether to go.间接引语位于句首时或者是间接引语提前时用whether不用if。如：Thank you, but whether Ill be free Im not sure at the moment.whether可引导一个让步状语从句表示“不管”、“无论”，而if不能。如：Whether he comes or not, we will begin our party on time.一句话总结：if一般只用于宾语从句中！（友情提示：if在宾语从句中可用将来时态，在它引导的条件状语从句中作“如果”讲时，要用现在完成时，后面语法中会讲到）（3）疑问词 + ever和no matter + 疑问词的区别。疑问词 + ever可引导名词性从句，在主从句中要充当一定的成分。如：Whoever breaks the rule must be punished.You can choose whatever you like in the shop.疑问词 + ever还可引导让步状语从句。如：Whatever you do, you must do it well.no matter + 疑问词只能引导让步状语从句。如：No matter what you do, you must do it well.No matter who breaks the rule, he must be punished.注意：复合疑问连接代词在主语、宾语、表语等从句中相当于：（它们主句中可作成分也可兼作从句中成分）原词相当于原词相当于what先行词+that或whichwhateveranything thatwhoanyone 或the person whowhoeveany person who或anyone whothathe或 the man whowhomeveranyone whom说明：1、带-ever的词往往有any的含义，语气较强。2、复合疑问连接代词还可引导副词性从句（后面会讲到）whoseveranyone whosewhicheveranyone who 或anything that或 which或either one/thing that如：Whoever leaves the room last ought to turn off the light.谁最后离开房间应关灯。（这里Whoever无论谁 ，在从句中作主语，在主句中也是作主语）。（4）when和where引导的同位语从句与定语从句的区别。when 和where前面的名词若是表示时间、地点的名词，则when和where引导的是定语从句，否则应为同位语从句。They put forward the question where they could get the money.This is the place where the accident happened.注意：when,where,why,how引导名词性从句，自已在从句中作状语，表示时间、地点、原因和方式。The question is where we can get so much money.问题是我们从哪里能弄到这么多钱。Where在从句中作地点状语。2、名词性从句中主句和从句的时态一致（1）宾语从句中主句和从句的时态保持一致，但如果从句中表示提示的是客观现象，虽然主句是过去时态，从句仍用一般现在时。如：Hello,I didnt know you were in London. How long have you been here?The teacher told us that light travels at a very high speed.（2）主语从句作主语相当于单数第三人称作主语，谓语动词用单数，如果由and 连接两个或两个以上的主语从句作主语时，谓语动词用复数；由两个或多个连接词引导一个主语从句，谓语动词用单数。如：When they will start and where they go have not been decided yet.When and where the meeting will begin has not been decided.3、名词性从句的词序：名词性从句在句中要用陈述句语序。Weve heard the news that well move into the new house. Whatever you say will interest us all. 二、分述：I. 主语从句 主语从句在从句中作主语，主语从句可以位于句首，但常见的主语从句多放在句末，句首则用形式主语it（当然由连接代词、连接副词或连词whether引导的主语从句前置、后置这两种结构可以互换）。但what、whatever 、whoever引导的主语从句除外，一般不能用it形式。 1. That the earth is round is true. = It is true that the earth is round. 2. Whether he will come hasnt been decided. = It hasnt been decided whether he will come. 注意：连词that, whether在从句中不担任句子成分，只起连接作用，不能省略。并且whether引导主语从句时不能用if代替。 3. Who let out the news remained unknown. = It remained unknown who let out the news. 4. How this happened is still a question.5. It is not clear when we will start.6. Which is right isnt known to us. 注意：who, which, how, when, where, why在所引导的主语从句中可担任主语，宾语，状语，不能省略。可以用形式主语it引导。 7. What he said at the meeting is important.8. Whoever leaves the office should tell me. 9. Whenever the Olympic Games will be held in Beijing is not known yet. 注意：who, whom, which, what等可以和ever构成合成词，引导主语从句和宾语从句。此类主语从句不能用it引导，引导词在句中担任句子成分，不能省略。注意：主语从句在疑问句或感叹句中时，多用it作形式主语。How strange it is that the children are so quiet!孩子们这么安静真奇怪！ 另外：有的“It 主语从句”已成为固定结构。如： a. It is +名词从句 It is a pity that we cant go.此类名词词组有：a pity, a shame, a fact, an honour, good news等 b. It is 形容词从句 It is clear that Tom has returned.能用此句型形容词常见的有：strange,natural, obvious, important, necessary,true,clear,likely,possible等 c. It is 过去分词从句 此类过去分词都是表示建议、命令、愿望的动词：said / reported / believed / known /hoped/expectedd. It +seem(s)/happen(s)/occurs+that从句 It happened that I wasnt there that day.那天恰好我不在那里。e. It doesnt matter +how/whether从句 It doesnt matter whether she will come or not.她是否能来这无关要紧。It + be +形容词+ that-从句 It is necessary that 有必要 It is important that 重要的是 It is obvious that 很明显It + be +名词词组+ that-从句 It is common knowledge that 是常识 It is a surprise that 令人惊奇的是 It is a fact that 事实是 It + be + -ed 分词+ that-从句 It is believed that人们相信It is known to all that 从所周知 It has been decided that 已决定It +不及物动词+ that-分句 It appears that似乎 It happens that碰巧 It occurred to me that 我突然想起提示：用it作形式主语的that-从句有以下四种不同的搭配关系： II. 表语从句 在复合句中用作表语的从句是表语从句。1. be, seem, look等动词后均可跟表语从句： My suggestion is that we should go shopping. It seems that it is going to rain. 2. as, as if,as though, because 也可引导表语从句。 It looks as if its going to rain. It was because I got up late. 3. 在非正式文体中，引导表语从句的that可以省略。如： The trouble is （that）he is ill. 注意：在表语从句中，当reason作主语时，表语从句表示原因时，引导词只能用that，不能用because、why。而用it,that,this做主语时，后面表语从句可用because、why引导。即：1）The+reason+连系动词+that引导表语从句如：他迟到的原因是因为他没有赶上早班车。 The reason why he was late was that he didnt catch the early bus.2）It(或This/That)+连系动词+because引导表语从句。 前面是结果，后面是原因。说明产生原因。3）It(或This/That)+连系动词+ why引导表语从句。 前面是原因，后面是结果。说明导致结果。本结构3：相当于It(或This/That)+连系动词+the reason+why引导定语从句。表“这就是的原因”。III. 宾语从句 在复合句中用作宾语的从句是宾语从句，当及物动词带双宾时，宾语从句用作直接宾语。 1. 作动词宾语 I dont know what I was thinking of.I expect （that）I shall be back on Sunday. 在口语中，that引导宾语从句时常常省略。但两个that从句并列时后边的that一般不省略。若有补语，则宾语从句要放到补语之后，在宾补前用形式宾语it. He doesnt want it to be known that he is going away. I consider it necessary that he should do it again.在think, believe, suppose, expect等动词之后，宾语从句中谓语的否定常转移到主句的谓语上。如：I dont think he will see you.We dont expect he is coming.注：此种用法主句的主语必须是一般现在时第一人称I或we. 而且它的反意疑问句的助动词由从句的助动词来定。I dont think he can do it, can he? I dont think you are right, are you? 在suggest, insist, demand, order, require 等表示建议，命令，要求的动词后，从句的谓语动词要用虚拟语气。即：（should）+动词原形。 I insisted that he （should）do it at once. She suggested that the work （should）be finished at once.句型 ：疑问词+do you think/believe/suppose(+从句主语)+从句谓语动词（+其他）？如：Who do you suggest be sent to work there?你建议派谁去那儿工作？ 2. 由wh-类引导的宾语从句可作介词宾语 ，that一般不作介词宾语，但在in和except、but, besides等表示“除外”的介词偶尔可以。当然这些介词后并不一定非要that引导宾语从句，也可以是what、then等词。The teacher is satisfied with what I said. 3. 作afraid, glad, certain, sure,happy ,surprised等形容词后可跟的宾语从句。(也称是修饰形容词的状语)。Im afraid that I will be late. Im glad that you passed the exam.4、宾语从句时态的呼应某些从句(特别是宾语从句)中的动词时态，常受主句谓语时态的制约。如果主句谓语动词为现在时或将来时，从句中的谓语可以不受影响。例如：Has he told you when he received the gift？Will you tell me how you two are getting along？如果主语谓语动词为过去时，从句谓语一般要跟着改为相关的过去时。I didnt know where they lived.He thought he was working for the people.asked him how long he had been waiting.但是，当宾语从句表示永恒真理时谓语可以不变：This proved that the earth is round. IV. 同位语从句 如果担任同位语的是个句子，则这个句子是同位语从句。同位语从句表示先行名词的具体内容，能跟同位语从句的名词常见的有news, idea, belief, doubt, fact, rumour, question, order, hope, thought, reply, problem, reason等。 引导同位语从句常用连词that，它在句中不担任句子成分，没有词意。除that外，还有whether, when, where, who, what, which, why, how等。可以引导同位语从句。 The rumour that there will be an earthq