高中英语语法从句讲解

1、.从句名词性从句在句子中起名词作用的句子叫名词性从句Noun Clauses。名词性从句的功能相当于名词词组，它在复合句中能担任主语、宾语、表语、同位语、介词宾语等，因此根据它在句中不同的语法功能，名词性从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。主语从句作句子主语的从句叫主语从句。主语从句通常由附属连词that，whether，if和连接代词what，who，which，whatever，whoever以及连接副词how，when，where，why等词引导。that在句中无词义，只起连接作用；连接代词和连接副词在句中既保存自己的疑问含义、又起连接作用，在从句中充当从句的成分。

2、例如：What he wants to tell us is not clear. 他要跟我们说什么，还不清楚。假如what-分句本身明显表示复数意义，比方what分句的动词和补语都是复数，那么主句动词也可用复数。如：What I say and think are none of your business.我说的和我想的都与你无关。注意：当what引导的名词性分句作主语时，主谓一致问题极为复杂。著名学者周海中教授在论文?关于what-分句作主语的主谓一致问题?中就这一问题做了深化研究，并给出了10种的主谓一致关系。这些一致关系值得英语学习者和使用者特别注意。有时为防止句子头重脚轻，常用形式

3、主语it代替主语从句作形式主语放于句首，而把主语从句置于句末。主语从句后的谓语动词一般用单数形式。常用句型如下：It + be + 名词+ that从句It + be + 形容词+ that从句It + be + 动词的过去分词+ that从句It +不及物动词+ that 从句另注意在主语从句中用来表示惊奇、不相信、可惜、理应如此等语气时，谓语动词要用虚拟语气“should +do，常用的句型有：It is necessary important, natural, strange, etc. that It is suggested requested, proposed, desired

4、, etc. that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：He has told me that he will go to Shanghai tomorrow.他已经告诉我他明天要去上海。We must never think that we are good in everything while

5、others are good in nothing.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, request, command, doubt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：I insist that she should do her work alone.我坚持要她自己工作。The commander ordered that troops should set off at once.司令员命令部队马上出发。2.用who, whom,

6、 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：I want to know what he has told you.我想知道他告诉了你什么。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“是否的意思讲时在以下情况下一般只能用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“o

7、r not时；e. 后接动词不定式时。例如：Whether there is life on the moon is an interesting question.月球上有没有生命是个有趣的问题。4. 注意宾语从句中的时态照应，当主句动词是如今时，从句根据自身的句子情况，而使用不同时态。例如：He studies English every day. 从句用一般如今时He studied English last term. 从句用一般过去时I know that he will study English next year. 从句用一般将来时he has studied English

8、since 2019. 从句用如今完成时当主句动词是过去时态could, would除外，从句那么要用相应的过去时态，如一般过去时，过去进展时，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，那么从句仍用如今时态。例如：The teacher told us that Tom had left us for America5. think, believe, imagine, suppose等等动词引起的否认性宾语从句中，要把上述主句中的动词变为否认式。即将从句中的否认形式移到主句中。例如：We dont think you are here. 我们认为你不在这。I dont bel

9、ieve he will do so. 我相信他不会这样做。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，表语从句位于联络动词后，有时用as if引导。其根本构造为：主语+ 系动词+ that从句。例如：The fact is that we have lost the game. 事实是我们已经输了这场比赛。Thats just what I want. 这正是我想要的。This is where our problem lies. 这就是我们的问题所在。That is why he didnt come to the meeting. 那就是他为

10、什么不到会的原因。It looks as if it is going to rain. 看上去天要下雨了。需要注意的，当主语是reason时，表语从句要用that引导而不是because。例如：The reason why he was late was that he missed the train by one minute this morning.【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。同位语从句同位语从句说明其前面的名词的详细内容。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、ho

11、pe、idea、information、message、news、order、problem、promise、question、request、suggestion、truth、wish、word等。例如：The news that we won the game is exciting.我们赢得这场比赛的消息令人冲动。I have no idea when he will come back home. 我不知道他什么时候回来。The thought came to him that Mary had probably fallen ill. 他想到可能玛丽生病了。同位语从句和定语从句的区别

12、：that作为关系代词，可以引导定语从句，充当句子成分，在从句中作宾语时可以省略；that引导同位语从句时，起连词的作用，没有实际意义，不充当句子成分，一般不能省略。试比较下面两个例句：I had no idea that you were herethat引导同位语从句，不能省略Have you got the ideathatthis book gives you of life in ancient Greece？that引导定语从句，作宾语，可以省略其他从句that从句5.1由附属连词that引导的从句叫做名词性that-从句。That只起连接主句和从句的作用，在从句中不担任任何成分，

13、本身也没有词义。名词性that-从句在句中能充当主 语、宾语、表语、同位语和形容词宾语，例如：主语：That she is still alive is her luck.她还活着全靠运气。宾语：John said that he was leaving for London on Wednesday.约翰说他星期三要到伦敦去。表语：The fact is that he has not been seen recently.事实是最近谁也没有见过他。同位语：The fact that he has not been seen recently disturbs everyone in his

14、 office.最近谁也没有见过他，这一事实令办公室所有的人不安。形容词宾语：I am glad that you are satisfied with your job.你对工作满意我感到很快乐。5.2That-从句做主语通常用it作先行词，而将that-从句置于句末，例如：It is quite clear that the whole project is doomed to failure.很清楚，整个方案注定要失败。Its a pity that you should have to leave.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：a. I

15、t + 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b. It + be + -ed分词+ that-从句It is believed that人们相信It is known to all that众所周知It has been decided that已决定c. It + be +名词+ 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d. It +不

16、及物动词+ that-从句It appears that似乎It happens that碰巧It occurred to me that我突然想起wh-从句6.1由wh-词引导的名词从句叫做名词性wh-从句。Wh-词包括who, whom, whose, whoever, what, whatever, which, whichever等连接代词和where, when, how, why等连接副词。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，例如：主语：How the book will sell depends on its author.书销

17、售如何取决于作者本人。直接宾语：In ones own home one can do what one likes.在自己家里可以随心所欲。间接宾语：The club will give whoever wins a prize. 俱乐部将给得胜者设奖。表语：My question is who will take over president of the Foundation.我的问题是谁将接任该基金会主席职位。宾语补足语：She will name him whatever she wants to. 她快乐给他起什么名字就取什么名字。同位语：I have no idea when h

18、e will return.我不知道他什么时候回来。形容词宾语：Im not sure why she refused their invitation.我尚不能肯定她为什么回绝他们的邀请。介词宾语：That depends on where we shall go.那取决于我们去哪儿。6.2Wh-从句做主语也常用先行词it做形式主语，而将wh-从句置于句末，例如：It is not yet decided who will do that job.还没决定谁做这项工作。It remains unknown when they are going to get married.他们何时结婚仍然

19、不明。if,whether从句7.1yes-no型疑问从句附属连词if, whether引导的名词从句是由一般疑问句或选择疑问转化而来的，因此也分别被称为yes-no型疑问句从句和选择型疑问从句，其功能和wh-从句的功能一样， 例如：主语：Whether the plan is feasible remains to be proved. 这一方案是否可行还有等证实。宾语：Let us know whether / if you can finish the article before Friday.请让我们知道你是否能在星期五以前把文章写完。表语：The point is whether

20、we should lend him the money.问题在于我们是否应该借钱给他。同位语：They are investigating the question whether the man is trustworthy.他们调查他是否值得信赖。形容词宾语：Shes doubtful whether we shall be able to come.她疑心我们是否可以前来。介词宾语：I worry about whether he can pass through the crisis of his illness.我担忧他是否能度过疾病的危险期。7.2选择性疑问从句选择性疑问从句由关

21、联词if/whetheror或whetheror not构成，例如：Please tell me whether / if they are Swedish or Danish.请告诉我他们是瑞典人还是丹麦人。I dont care whether you like the plan or not.我不在乎你是否喜欢该方案。if和whether的区别：1、 在动词不定式之前只能用whether。如：I cant decide whether to stay. 我不能决定是否留下。2、 在whether or not 的固定搭配中。如：I want to know whether its goo

22、d news or not . 我想知道是否是好消息。3 、在介词后，只能用whether。如：His father is worried about whether he lose his work .他的父亲担忧是否会失去工作。4、宾语从句放在句首表示强调时，只能用whether。如：Whether this is true or not, I really dont know.这是否真的，我真的不知道。5、用if会引起歧义时，只用whether。如：Could you tell me if you know the answer这句话有两种意思：“你能告诉我是否知道答案吗？或“假如你知道

23、答案，请告诉我，好吗？。如用whether可防止歧义。形容词性从句定语从句Attributive Clauses在句中做定语，修饰一个名词或代词，被修饰的名词，词组或代词即先行词。定语从句通常出如今先行词之后，由关系词关系代词或关系副词引出。含义：在定语的位置上是个句子。why关系副词why主要用于修饰表原因的名词主要是the reason，同时它在定语从句中用作原因状语。如：We dont know the reason why he didnt show up.我们不知道他为什么没有来。She didnt tell me the reason why she refused the off

24、er.她没跟我讲她回绝这项工作的原因。与关系副词when和where不同，why可以换成that或省略。如：Thats one of the reasons why, that I asked you to come.这就是我请你来的原因之一。另外，与关系副词when和where可以引导非限制性定语从句不一样，why只能引导限制性定语从句，不能引导非限制性定语从句。如：他失去工作的主要原因是他喝酒。误：The main reason, why he lost his job, was that he drank.正：The main reason why he lost his job was

25、 that he drank.when关系副词when主要用于修饰表时间的名词，同时它在定语从句中用作时间状语。如：There comes a time when you have to make a choice.你必须作出抉择的时候到了。Gone are the days when they could do what they liked.他们为所欲为的日子一去不复返了。Well put off the picnic until next week, when the weather may be better.我们将把野餐推延到下星期，那时天气可能会好一点。注意不要一见到先行词为时间名词，就以为一定要用关系副词when来引导定语从句，同时还要看它在定语从句中充当什么成分假如在定语从句中用作时间状语，就用when；假如在定语从句中不是用作时间状语，而是用作主语或宾语，那就不能用when，而要用that, which等。如：Dont forget the time that, which Ive told you.不要忘记我告诉你的时间。关系代词that / w