1、英語語法知識難點(三)編 稿：李俊和審 稿：畢 勤 責編: 隋 瑜(十)情態動詞與助動詞I 要點助動詞本身無意義，在句中幫助主要動詞構成一定的時態，語態、語氣，或是幫助構成否定句和疑問句，常用的助動詞有be, do, have, shall(should), will(would).情態動詞表一定的詞義，本身并不表示動作或狀態，而僅僅表達說話人的態度，它在句中須和主要動詞一起構成謂語，主要的情態動詞有 can(could), may(might), must, have to, ought to, need, dare, shall, should, will, would.1、 can 能，

2、可以，表說話人同意，許可還可表客觀條件許可，如 :You can go now.提建議或請求時可用 can I, can you 表客氣，如 Can I buy you a drink?can 和 be able to 表能力時的區別。can 表一般具有的能力， be able to 表在特定條件下的能力， 如 :Although the driver was badly hurt, he was able to explain what had happened.2、 may( 1)、可以，表說話人同意，許可或請求對方許可。 You may go.(2)、(現在和將來)可能，也許，只用于肯定

3、句和否定句中，如 He may not be right.3、 must, have tomust 表主觀上的必須， have to 表客觀上的必須，如 :It's getting late. I have to go. -Must I go now. -Yes, you must.(No, you needn't./ No, you don't have to.)4、 need, dare 這二詞有實意動詞和情態動詞兩種詞性， 如用作實意動詞后接動詞不定式to do，如用作情態動詞后接動詞原形。 Need I go now? -Yes, you must./No, y

4、ou needn't.)5、 shall 用于第一人稱疑問句中表說話人征求對方的意見或向對方請求，如， Shall we begin our lesson?用于二、三人稱陳述句，表說話人命令、警告、允諾、威脅等口吻，如 : You shall fail if you don't work harder.6、 should 表應該，意為有責任，有義務。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

5、 book?" "Yes, I will." ，8、 should have done 表應該做而未做must have done 表對過去事實的肯定推測could have done 表本可以做某事9、判斷句：肯定句用must, 否定句用 can't, 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 can't be in the office. He is at home.He couldn't

6、have cleaned the classroom, because he didn't come here today.He might be in the office, I am not sure.He might have cleaned the room, I suppose.II 例題例 1， They to walk in the street at night.A. didn't dare B. not dared C. not dare D. dared not解析，該題答案為 A， 此空需選一動詞作謂語，因為后面是 to walk, didn't

7、dare 是行為動 詞 dare 過去時態的否定形式。例 2， When he was very old, Mr. Smith sit for hours without saying a word.A. would B. should C. must D. used解析，該題答案為 A, would 此處表過去的傾向性，習慣性動作，意為 "總是 "如: Whenwe were children, we would go swimming every summer.（十一）句子種類I 要點句子按使用目的可分為陳述句、疑問句、祈使句和感嘆句；按結構又分為簡單句、并列句和復合句

8、。1、陳述句的否定（ 1） 在含有賓語從句的主從復合句中， 當主句的謂語動詞是think, expect, believe, suppose,guess, fancy, imagine 等，且主句主語是第一人稱時，賓語從句謂語的否定習慣上要移到主句 謂語上，如 : I don't think he is right.（ 2） 含有否定意義的副詞 never, seldom, hardly, scarcely, rarely, barely 的句子應視 為否定句，如 : I have never been there before.2、反意疑問句（ 3） ） need 和 dare 既可

9、作情態動詞， 又可作實意動詞， 在反問部分須加以區別， 如 Weneedn't leave, need we? We don't need to leave, do we?（ 2） 陳述部分出現否定意義的副詞或代詞如 never, seldom, few, hardly, little等時，反問部分須用肯定形式如： He seldom comes, does he?（ 3） 陳述部分用不定代詞作主語時，反問部分的主語用 it ，如： Nothing can stop me, canit?陳述部分用 everybody, everyone, somebody, someone ，

10、等作主語時，反問部分常用 it ，有 時也用 they ，如 :Everybody knows that, don't they?（ 4） 陳述部分包括used to 時， 反問部分可有兩種形式， 如 : You used to get up early, usedn't（didn't） you?（5）陳述部分是"there + be"結構時，反問部分用 there ,如:There's something wrong with you, isn't there?（ 6） 陳述部分是含有賓語從句的主從復合句時，反問部分的主語和謂語應和

11、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 + 賓語從句時，反問部分須和從句的動詞保持一致，如，I don't think he is right, is he? I don't believe he does that, does he?3、感嘆句用 what 或 how,What a beautiful park it is.How beautiful a park it is. How beautiful the park is.How we work

12、ed!4、祈使句Take care!Don't stand there.Please open the door for the old lady.II 例題例 1， Don't forget to post the letter, ?A. will you B. do you C. won't you D. shall you解析：該題答案為 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 (won't, can, can't, could) you?例 2，

13、Let's go out for a walk, ?A. will you B. won't you C. shall we D. do we解析：該題答案為 C, let's后加上shall we來表語氣婉轉、客氣，而在let us后加上will you。例 3， He hardly writes to you, ?A. doesn't he B. does he C. do they D. has he解析：該題答案為 B， hardly 否定副詞，反問部分要用肯定形式。（十二）各種從句I 要點根據從句在句中的句法功能，從句可分為名詞性從句、定語從句和狀語從

14、句。1、 名詞性從句（ 1） 主語從句What he wants is a piece of paper.It is believed that he can solve the problem.注：主語從句的謂語動詞用單數。（ 2）賓語從句I don't know how to solve the problem.Do you know where he lives?（ 3）表語從句The problem is who can help me.This is why I came here.（ 4）同位語從句I have no idea where he went.I heard t

15、he news that he would come.同位語從句用 that 引導， 常跟在 fact, idea, news, promise, thought, message, hope, belief, doubt 等詞后， that 在從句中不作任何成分。2、定語從句在復合句中，修飾某一名詞或代詞，或修飾整個主句的從句叫做定語從句，引導定語從句的關系代詞有 who, whom, whose, which, that, as, 和關系副詞when, where, why 。（ 1） that 指物時一般可與which 互換，但在下列情況下，要用 that 而不用 which 。a. 先

16、行詞有 all, everything 等不定代詞時，如，Everything （that） he did is wrong.b. 先行詞被 all, every, no, some, any, little, much等修飾時，如，I'll read all the books （that） you lend me.c. 先行詞被序數詞或形容詞最高級修飾時，This is the first letter (that) the boy has written.d. 先行詞被 the only, the very, the same, the last修飾時，如He is the ve

17、ry man (that) I'm looking for.e. 只用 which 的情況在介詞后或在非限定性定語從句中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作關系副詞This is the room where I worked.This is the room which I stayed in.I remembered the day when we lived there.I

18、 remembered the day that I spent there.g. as 和 whichas 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、狀語從句在復合句中起狀語作用的從句叫做狀語從句。 狀語從句可分為時間狀語、 地點狀語、 原因狀語、目的狀

19、語、結果狀語、條件狀語、行為方式狀語、比較狀語、讓步狀語等多種。II 例題例 1、 I accept the gift or refuse it is none of your business.A. If B. Whether C. Even if D. No matter when解析：該題答案為B。 whether 可以和 or 連用， if 不可以，此外if 一般僅用于賓語從句。例 2、 The way these comrades look at problems is wrong.A. where B. in that C.X D. with which解析：該題答案為 C,先行詞

20、是way,定語從句中用that或in which來引導或不填。例 3， a long time since I saw you last time.A It was B. It is C. It had been D. It can be解析：該題答案為 B, It is + 時間數+ since引導的從句是一個句型，意為"從時候以來過了多久了。 "（十三）主謂一致I 要點謂語受主語支配， 須和主語在人稱和數上保持一致， 這叫做主謂一致， 主謂一致包括語法一致、意義上一致和就近一致。1、語法上一致（ 1）、以單數名詞或代詞，動詞不定式短語、動名詞短語或從句作主語時，謂語動詞

21、要用單數，主語為復數時，謂語用復數，如，To work hard is necessary for a student.（2）、用and或bothand連接的并列主語，謂語動詞用復數，如，Both he and I are right.但并列主語如果指的是同一人，同一事物或同一概念，謂語動詞用單數，如 , His teacher and friend is a beautiful girl.（ 3）、主語是單數時，盡管后面跟有as well as, but ,except, besides, with ,along with,together with, like 等，謂語動詞仍用單數，如，T

22、he teacher as well as his students is excited.（4）、某些不定代詞，如做主語，謂語動詞要用單數，如:Everyone has a book.（ 5）、一些只有復數形式的名詞，如people, cattle, clothes 等作主語時，謂語動詞要用復數，如， A lot of people are dancing outside.2、意義上一致（ 1）、表時間、距離、價格、度量衡等的名詞作主語時，謂語動詞通常用單數，如，Twenty years is not a long time.（ 2）、表示總稱意義的名詞public, police, cattle,