英语语法知识难点3

1、英语语法知识难点（三）编 稿：李俊和 审 稿：毕 勤 责 编: 隋 瑜（十）情态动词与助动词 I 要点助动词本身无意义，在句中帮助主要动词构成一定的时态，语态、语气，或是帮助构成否定句和疑问句，常用的助动词有be, do, have, shall(should), will(would).情态动词表一定的词义，本身并不表示动作或状态，而仅仅表达说话人的态度，它在句中须和主要动词一起构成谓语，主要的情态动词有can(could), may (might), must, have to, ought to, need, dare, shall, should, will, would.1、can

2、能，可以，表说话人同意，许可还可表客观条件许可，如:You can go now.提建议或请求时可用can I, can you表客气，如Can I buy you a drink?can和be able to表能力时的区别。can表一般具有的能力，be able to表在特定条件下的能力，如:Although the driver was badly hurt, he was able to explain what had happened.2、may（1）、可以，表说话人同意，许可或请求对方许可。You may go.（2）、（现在和将来）可能，也许，只用于肯定句和否定句中，如He ma

3、y not be right.3、must, have tomust表主观上的必须，have to表客观上的必须，如:Its getting late. I have to go. -Must I go now. -Yes, you must.(No, you neednt./ No, you dont have to.)4、need, dare这二词有实意动词和情态动词两种词性，如用作实意动词后接动词不定式to do，如用作情态动词后接动词原形。Need I go now? -Yes, you must./No, you neednt.)5、shall用于第一人称疑问句中表说话人征求对方的意

4、见或向对方请求，如，Shall we begin our lesson?用于二、三人称陈述句，表说话人命令、警告、允诺、威胁等口吻，如: You shall fail if you dont work harder.6、should表应该，意为有责任，有义务。如:We should try our best to make our country more beautiful.7、will表有做某事的意志、意愿、安心、打算，如 Will you lend me your book? Yes, I will.，8、should have done表应该做而未做must have done表对过去

5、事实的肯定推测could have done表本可以做某事9、判断句：肯定句用must, 否定句用cant, 不太肯定用may, mightHe must be in the office now.He must have gone to bed, for the light is out.He cant be in the office. He is at home.He couldnt have cleaned the classroom, because he didnt come here today.He might be in the office, I am not sure.H

6、e might have cleaned the room, I suppose.II 例题例1，They _ to walk in the street at night.A. didnt dare B. not dared C. not dare D. dared not解析，该题答案为A， 此空需选一动词作谓语，因为后面是to walk, didnt dare是行为动词dare过去时态的否定形式。例2，When he was very old, Mr. Smith _ sit for hours without saying a word.A. would B. should C. mu

7、st D. used解析，该题答案为A, would此处表过去的倾向性，习惯性动作，意为总是如: When we were children, we would go swimming every summer.（十一）句子种类I 要点句子按使用目的可分为陈述句、疑问句、祈使句和感叹句；按结构又分为简单句、并列句和复合句。1、陈述句的否定（1） 在含有宾语从句的主从复合句中，当主句的谓语动词是think, expect, believe, suppose, guess, fancy, imagine等，且主句主语是第一人称时，宾语从句谓语的否定习惯上要移到主句谓语上，如: I dont thi

8、nk he is right.（2） 含有否定意义的副词never, seldom, hardly, scarcely, rarely, barely的句子应视为否定句，如: I have never been there before.2、反意疑问句（1） need和dare 既可作情态动词，又可作实意动词，在反问部分须加以区别，如We neednt leave, need we? We dont need to leave, do we?（2） 陈述部分出现否定意义的副词或代词如never, seldom, few, hardly, little等时，反问部分须用肯定形式如：He seld

9、om comes, does he?（3） 陈述部分用不定代词作主语时，反问部分的主语用it ，如：Nothing can stop me, can it?陈述部分用everybody, everyone, somebody, someone，等作主语时，反问部分常用it，有时也用they，如:Everybody knows that, dont they?（4） 陈述部分包括used to 时，反问部分可有两种形式，如: You used to get up early, usednt (didnt) you?（5） 陈述部分是there + be结构时，反问部分用there，如:There

10、s something wrong with you, isnt there?（6） 陈述部分是含有宾语从句的主从复合句时，反问部分的主语和谓语应和主句保持一致，如: He never told others what he thought, did he?但，如果是I think , I believe等 +宾语从句时，反问部分须和从句的动词保持一致，如，I dont think he is right, is he? I dont believe he does that, does he?3、感叹句用what或how, What a beautiful park it is.How be

11、autiful a park it is.How beautiful the park is.How we worked!4、祈使句Take care!Dont stand there.Please open the door for the old lady.II例题例1，Dont forget to post the letter, _ ?A. will you B. do you C. wont you D. shall you解析：该题答案为A， 在否定句、祈使句后只用will you?，但肯定的祈使句后可用如，Wait for me, will (wont, can, cant, c

12、ould) you?例2，Lets go out for a walk, _ ?A. will you B. wont you C. shall we D. do we 解析：该题答案为C，lets后加上shall we来表语气婉转、客气，而在let us后加上will you。例3，He hardly writes to you, _ ?A. doesnt he B. does he C. do they D. has he解析：该题答案为B，hardly否定副词，反问部分要用肯定形式。（十二）各种从句I要点根据从句在句中的句法功能，从句可分为名词性从句、定语从句和状语从句。1、 名词性从句

13、（1） 主语从句What he wants is a piece of paper.It is believed that he can solve the problem.注：主语从句的谓语动词用单数。（2）宾语从句I dont know how to solve the problem.Do you know where he lives?（3）表语从句The problem is who can help me.This is why I came here.（4）同位语从句I have no idea where he went.I heard the news that he wou

14、ld come.同位语从句用that引导，常跟在fact, idea, news, promise, thought, message, hope, belief, doubt等词后，that在从句中不作任何成分。2、定语从句在复合句中，修饰某一名词或代词，或修饰整个主句的从句叫做定语从句，引导定语从句的关系代词有who, whom, whose, which, that, as,和关系副词when, where, why。（1）that指物时一般可与which互换，但在下列情况下，要用that而不用which。a. 先行词有all, everything等不定代词时，如，Everything

15、 (that) he did is wrong.b. 先行词被all, every, no, some, any, little, much等修饰时，如，Ill read all the books (that) you lend me.c. 先行词被序数词或形容词最高级修饰时，This is the first letter (that) the boy has written.d. 先行词被the only, the very, the same, the last修饰时，如He is the very man (that) Im looking for.e. 只用which的情况在介词后

16、或在非限定性定语从句中This is the book about which we have talked a lot.The book, which he gave me yesterday, is very interesting.f. where和when作关系副词This is the room where I worked.This is the room which I stayed in.I remembered the day when we lived there.I remembered the day that I spent there.g. as和which as

17、可以放于句首，而which 不可以As you know, he is good at English.three of them 和three of whichI have a lot of books, three of which are in Russian.I have a lot of books and three of them are in Russian.3、状语从句在复合句中起状语作用的从句叫做状语从句。状语从句可分为时间状语、地点状语、原因状语、目的状语、结果状语、条件状语、行为方式状语、比较状语、让步状语等多种。II 例题例1、 _ I accept the gift

18、 or refuse it is none of your business.A. If B. Whether C. Even if D. No matter when解析：该题答案为B。whether可以和or连用，if不可以，此外if一般仅用于宾语从句。例2、The way _ these comrades look at problems is wrong.A. where B. in that C.X D. with which解析：该题答案为C，先行词是way，定语从句中用that或 in which来引导或不填。例3， _a long time since I saw you la

19、st time.AIt was B. It is C. It had been D. It can be 解析：该题答案为B，It is +时间数+ since引导的从句是一个句型，意为从时候以来过了多久了。（十三）主谓一致I 要点谓语受主语支配，须和主语在人称和数上保持一致，这叫做主谓一致，主谓一致包括语法一致、意义上一致和就近一致。1、语法上一致（1）、以单数名词或代词，动词不定式短语、动名词短语或从句作主语时，谓语动词要用单数，主语为复数时，谓语用复数，如，To work hard is necessary for a student.（2）、用and或bothand连接的并列主语，谓语

20、动词用复数，如，Both he and I are right.但并列主语如果指的是同一人，同一事物或同一概念，谓语动词用单数，如, His teacher and friend is a beautiful girl.（3）、主语是单数时，尽管后面跟有as well as, but ,except, besides, with ,along with, together with, like等，谓语动词仍用单数，如，The teacher as well as his students is excited.（4）、某些不定代词，如做主语，谓语动词要用单数，如:Everyone has a book.（5）、一些只有复数形式的名词，如people, cattle, clothes等作主语时，谓语动词要用复数，如，A lot of people are dancing outside.2、意义上一致（1）、表时间、距离、价格、度量衡等的名词作主语时，谓语动词通常用单数，如，Twenty years is not a long time.（2）、表示总称意义的名词public, police, cattle, clothes等作主语时，谓语动词用复数，如，