中考英语助动词和情态动词讲解

中考英语助动词和情态动词讲解(一)助动词助动词的特殊用法1. 协助主要动词构成谓语动词词组的词叫助动词。

被协助的动词称作主要动词。

助动词本身没有词义，不可单独使用。

--- I didn’t see her yesterday.( didn’t是助动词，无词义，see是主要动词，有词义）2. 助动词(主要是be, do 和have ）协助主要动词完成以下功能，可以用来：(1) 表示时态--- He has got married.(2) 表示语态--- He was sent to England.(3) 构成疑问句：--- Have you seen the doctor yet?(4) 与否定副词not 合用，构成否定句：-- I don’t like him.(5) 加强语气：--- Do come to the party tomorrow evening.3. 常用的助动词的其他用法(1) 以be 为中心词构成的半助动词be to ( 将要), be about to ( 即将要), be goingto (打算), be sure to ( 肯定), be likely to (很有可能）等，后接动词原形。

---- Autumn harvest is about to start.---- They are sure to have a good ending.(2) 以have 为中心词的半助动词have got to (必须), have to ( 不得不，必须), hadbetter ( 最好---)，后接动词原形--- I ‘ve got to telephone him now.--- We’ll have to stay here for the night.(3) 以seem, appear, happen 等动词为中心的半助动词，后可接带to的动词不定式，可以转化为it seems / appears / happens + that 结构--- These grammar rules seem to be easy to me.= It seems that these grammar rules are easy to me.(二）情态动词：1.情态动词的特殊用法：(1) shoulda. 表示义务或责任，意为“应该”，可用于各种人称--- As a monitor, you should help him.--- She shouldn’t waste any time in playing video games.b. 用于第一人称时可以表示说话人的一种谦逊，客气, 委婉的语气--- I should advise you not to do that.c. 用在if引导的条件状语从句中，表示一件事听起来可能性很小，但也不是完全没有可能，相当于“万一”--- Ask her to ring me up if you should see her.d. Why / How +should 结构表示说话人对某事不能理解感到意外，惊异等意思，意为“竟会”--- Why should you be so late today?--- I don’t know why you should think that I did it.注意：ought to 表义务，意为“应该”，语气比should 弱( 2) woulda. 表示愿意，可用于各种人称--- They would not let him in because he was poorly dressed.--- I said I would do anything for you.b. 表示委婉地提出请求建议或看法，可用于第二人称--- Would you like another cup of coffee?c. 表示过去反复发生的动作或过去的一种倾向---Every time she was in trouble, she would go to him for help.(3) dare 作情态动词和实义动词的用法区别dare 的用法同need, 既可作情态动词，也可作实义动词。

作实义动词时，在肯定句中，dare 后面通常接带to 的不定式，在否定和疑问句中，后面既可接带to 的不定式，也可接不带to 的不定式。

--- I wonder how he dared say that to the teacher.( 情态动词）--- We didn’t dare try a shot. ( 实义动词，否定句中省略to)2. 情态动词后跟完成式和进行式的用法(1) 情态动词后跟完成式，表“ 应当已经---”，“想必已经—”，“本来可以—”等意义。

不同的情态动词与动词完成形式连用表示不同的含义，通常有下列几种情况：a. can’t / couldn’t have done sth. 表示推测过去不可能发生的事情--- I didn’t see her in the meeting room this morning. She couldn’t have spoken at the meeting.--- He can’t / couldn’t have attended the meeting yesterday.b. must have done sth. 表示推测过去必然发生的事，语气较强，具有“肯定”的意思。

--- I didn’t hear the phone. I must have been asleep.注意：may ( might ) have done sth. 推测过去时间里可能发生的事情，用于肯定句和否定句--- You may have read about it.c. ought to / should have done sth. 表示本应该做某事而实际上没有做。

其否定式表示某种行为不该发生但却发生了。

--- I should have finished the work earlier.--- You ought to have thrown the old clothes away.d. “might / could +动词完成形式” 可表示婉转地责备某人过去应做某事而未做，另外“might / could+ 动词完成形式”经常表示过去可能做了某事--- You could ( might ) have been more careful.注：could +完成式表示本来能够做成某事，但结果没能做成，含有遗憾的意味。

--- I stayed at a hotel while in New York.--- oh, did you ? You could have stayed with Mary.注：could +完成式用于否定和疑问句中时，表示过去不可能或对可能性提出疑问。

--- My sister met him at the Grand Theatre yesterday afternoon, so he couldn’t have attended your lecture.e. needn’t have done 表示本没必要做某事而做了。

--- He needn’t have worried about it.注：“ did not need to +动词原形” 表示过去没有必要做某事而结果也没做。

--- As it was Sunday, he didn’t need to go to work.( 没必要上班，因而也没去）--- You needn’t have come to work. It is Sunday today.( 没必要上班，但却来了）( 2) 情态动词后跟进行式，表示“想必正在---”，“可能正在---”，“应当正在---”等意--- It’s twelve o’clock. They must be having lunch.--- They may be discussing this problem.--- She shouldn’t be working like that. She’s weak.3. 容易用错的情态动词(1) can 和be able toa. can 表示长期固有的自然能力，只有两种时态形式。

现在时can 和过去时could.注：be able to 表示经过努力克服困难后才获得的能力，且be able to 有多种时态形式。

--- After three months’ study, I am able to drive a car now.--- Mary can play the piano. She has been able to play it since she was 5.b. 用在过去时中，could 经常表示具有能力能够做某事而was / were able to则表示“过去通过努力，克服困难做成了某事”。

--- He could swim across the English Channel , but he didn’t feel like it that day.--- Yesterday I was able to get home before the heavy rain.(2) must 和have toa. must 表示说话人的主观看法，而have to 则强调客观需要。

--- The film is not interesting. I really must go now.--- I told her that she must give up smoking.--- We had to get everything ready that night.b. must 只有一种形式，have to 则涉及人称，时态等方面的变化形式。

两者的否定意义大不相同。

--- You mustn’t go. ( 带有很强的语气，表示“禁止，不允许”)---You don’t’ have to go. ( 表示“不必” ）c. 询问对方的意见时应用must--- Must I clean all the rooms?(3) would 和used toa. 都可表示过去的习惯，但used to 强调现在已发生变化，而would 只表示过去的习惯，不含有与现在不同的意思。

--- Family violence is still a problem, but it used to be worse.--- Sometimes she would bring some small presents when she was in a good mood.b. used to 可表示过去的习惯动作和经常的情况，而would 只表示过去的习惯动作--- He used to / would smoke while writing.--- He used to be fat.练习1. It have been Tom that parked the car here, as he is the only one with a car.A. mayB. canC. mustD. should C2. Cable television is very popular nowadays because it ________ provide moreprogrammes.A. canB. needC. mustD. should A3. Children under 12 years of age in that country ____ be under adultsupervision when in a public library. AA. mustB. mayC. canD. need4. You might just as well tell the manufacturer that male customers______ not like the design of the furniture. CA. mustB. shallC. mayD. need5. There be any difficulty about passing the road test since you havepractised a lot in the driving school. CA. mustn'tB. shan'tC. shouldn'tD. needn't6. You know he is not going to let us leave early if we get thework done. AA. can'tB. may notC. shouldn'tD. mustn't。