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高考英语二轮语法复习学案(助动词与情态动词)(一)助动词有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: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。 用于命令。Youre 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 doesnt 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 wasnt 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 Dongs? (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 mustnt. Its 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 mustnt,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 mustnt touch the fire. (2)对以must提出的疑问句,如作否定回答时,要用neednt或用dont (doesnt) have to (不 必)来回答,而不用mustnt,因为mustnt表示的是“禁止”或“不许可”之意,如:- Must we finish the work tomorrow? - No, you neednt (dont 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 Dongs. 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: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? 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。如:- When did you answer her letter? - Only yesterday. - Its too late. You could have answered it earlier , I am sure. (2)may, might后接完成式的用法 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. 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 di dnt 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 isnt 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 didnt) 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 oughtnt 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 neednt 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)neednt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 neednt 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. 11、will的基本用法(1)用于各人称,可以表示“意志”或“决心”,如:I have told him again and again to stop smoking, but he will not li
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