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初中英语复习要点:助动词与情态动词

时间:2021-06-23 12:22:37 英语 我要投稿

初中英语复习要点:助动词与情态动词

  (一)助动词

初中英语复习要点:助动词与情态动词

  有be, have, do, will, shall,它们本身没有词义,只和实义动词的一定形式构成复合谓语,用来表示时态和语态,构成否定、疑问及加强语气等。

  1、be (am, is, are, were, been)

  (l)"be + -ing"构成进行时态;(2)"be + 过去分词"构成被动语态;(3)"be + 动词不定式"构成复合谓语:①表示按计划安排要发生的事。The prime minister is to visit Japan next year. 总理将于明年访问日本。② 用于命令。You're to do your homework before you watch TV.你得做完了作业才能看电视。

  2、have (has, had)

  (1)"have+过去分词"构成完成时态。如:Have you seen the film ? (2)"have been + -ing"构成完成进行时态。如:What have you been doing these days? 这些日子你一直在干什么?

  3、do (does, did)

  (1)"do not + 动词原形"构成行为动词的否定式。如:His brother doesn't like playing basket.;(2)"Do + 主语 + 动词原形"构成行为动词的一般疑问句。Does he go to school by bike every day? (3)"do + 动词原形"用于祈使句或陈述句中表示加强语气。如:I did go to see him, but he wasn't in我确实去看望他了,但他不在家。Do do some work. 请一定做点什么;(4)代替前面刚出现的动词以避免重复。My mother told me to go to bed early. So I did.

  4.will, shall (would, should)

  "will (shall+动词原形"构成一般将来时,一般来说shall用于第一人称,will用于第二人称或第三人称,口语中常用will代替shll,如:We will have a meeting to discuss the problem.

  (二)情态动词

  情态动词表示说话人对某一动作或状态的态度,可以表示"可能"、"可以"、"需要"、"必须"或"应当"等之意。情态动词没有人称和数的变化。但不能单独作谓语动词用,必须和不带to的不定式连用构成谓语动词。只有情态动词ought要和带to的动词不定式连用,在句中作谓语用。

  将情态动词置于主语之前即构成其疑问式,在情态动词之后加not既构成其否定式。现将各情态动词的基本用法分述如下:

  1、can和could (could为can的过去式) 的基本用法

  (1)表示能力,如:He can speak English better than you. (2)在疑问句和否定句中表示"怀疑"、"猜测"或"可能性",如:Can this green bike be Liu Dong's? (3)表示"许可"时can可以和may换用,如:You can (may) go home now. (4)如果要表示语气婉转,可用could代替can,这时could不再是can的过去式,如:Could you come again tomorrow? (5)can和be able to都可表示能力,两者在意思上没有什么区别。但是can只能有现在式和过去式,而be able to则有更多的形式,如:He will be able to do the work better.

  2、may和might (might为may的过去式)的基本用法

  (1)表示允许或征询对方许可,有"可以"之意,如:You may use my dictionary. 在回答对方说"可以做某事"或"不可以做某事"时,一般多不用may或 may not,以避免语气生硬或不容气。而用比较婉转的说法进行回答。如:---- May I use this dictionary? ---- Yes, please. 或 ---- Certainly. 在请求对方许可时,如果Might I…? 就比用May I…? 语气更婉转些,如:May I have a look at your new computer? 但是表示"阻止"或"禁止"对方做某事时,要用must not代替may not,如:---- May we swim in this lake? ---- No, you mustn't. It's too dangerous. (2)may或 might都可以表示可能性,表示"或许"、"可能"之意,如果用might表示可能性,则语气更加不肯定,如:They may (might) be in the library now .

  3、must的基本用法

  (1)must表示"必须"、"应该"之意,其否定式 must not,缩写形式为 mustn't,表示"不应该","不准"、"不许可"或"禁止"之意,如:We must study hard and make progress every day. You mustn't touch the fire. (2)对以must提出的疑问句,如作否定回答时,要用needn't或用don't (doesn't) have to (不 必)来回答,而不用mustn't,因为mustn't表示的是"禁止"或"不许可"之意,如:---- Must we finish the work tomorrow? ---- No, you needn't (don't have to), but you must finish it in three days. (3)在肯定句中must可以表示推测,表示"一定"或"必定"之意,如:---- Whose new bike can it be? ---- It must be Liu Dong's. I know his father has just bought him a new one.

  4、can, could, may, must后接完成式的用法

  (1)can, could后接完成式的用法:①在否定句或疑问句中表示对过去发生过的事情的"怀疑"或"不肯定"的态度,Could he have said so? ②在肯定句中,可以表示过去可能做到而实际并没做到的事情,有"劝告"或"责备"的语气,英语语法《语法复习十一:助动词与情态动词》。如:---- When did you answer her letter? ---- Only yesterday. ---- It's too late. You could have answered it earlier, I am sure. (2)may, might后接完成式的用法 ①表示对过去某事的推测,认为某一件事情在过去可能发生了。如果使用might,语气就比较婉转或更加不肯定,如:Mary might have learned some Chinese before. ②可以表示过去本来可以做到而实 际没有做到的事情,有"劝告"或"责备"的语气,如:You didn't do the work well that day. You might have done it better. (3)must后接完成式的用法:表示对过去某事的推测,认为某事在过去一定做到 了,如:Liu Dong isn't in the classroom. He must have gone to the library.

  5、have to 的基本用法:

  have to和must的意义相近,只是 must侧重表示说话人的主观看法,而have to 则表示客观需要,如:I must study hard. I had to give it up because of illness.

  6、ought to的`基本用法

  (l)表示根据某种义务或必要"应当"做某事,语气比should强,例如:Everyone ought to obey the traffic regulations. (2)表示推测,注意与must表示推测时的区别:He must be home by now .(断定他已到家),He ought to be home by now .(不十分肯定),This is where the oil must be.(比较直率) ,This is where the oil ought to be. (比较含蓄) ;(3)"ought + have+ 过去分词"表示过去应做某事而 实际未做。例如:You ought to have helped him. (but you didn't) 这时,ought与 should可以互相换用。注意,在美国英语中ought to 用于否定和疑问句时to可以省略。例如:Ought you smoke so much? You oughtn't smoke so much.

  7、dare的基本用法

  (l)dare (dared为其过去式) 作情态动词用时,主要用于否定句,疑问句和条件从句中,如:Dared he bread the traffic regulations again? (2)在现代英语中dare常用作行为动词,其变化与一般行为动词相同,如:She dares to stay at home alone at night.

  8、need的基本用法

  (1)need作情态动词用时,主要用于否定句和疑问句中,如:He needn't worry about us now. (2)need也可作为行为动词用,可用于肯定句,否定句和疑问句中,其后可接名词、代词、动名词或带 to 的动词不定式为其宾语。如:You need to practise reading aloud every day. (3)needn't后接完成式可以表示过去做了一件本来不必要做的事情,如:---- Did you answer the letter yesterday? ---- Yes, I did. ---- But you needn't have answered it.

  9、shall的基本用法

  (1)shall用作情态动词时,用于第二、三人称,表示说活人的意愿,可表示"命令"、"警告"、"强制"、"威胁"或"允诺"等意,如:He shall go first, whether he wants to or not. (2)在疑问句中,shall用于第一、三人称,表示说话人的征询对方意见或请求指示,如:Shall I open the door?

  10、should的基本用法

  (1)should作为情态动词可以表示"建议"或"劝告",有"应该"之意,如:You should learn from each other. (2)should后接完成式表示过去没有做到本来应该做的事情,或是做了本来不应该做的事情。如:You should have give him more help.

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