1、Modal Verbs 1,had bettershouldought to,Had better,Had better 是一个固定词组，表示可取，意为“最好”，“应该”，常用一般式。 E.g, Youd better get some rest. Wed better stop now. You better say yes if they ask you this question.(有时可以省略had),Should,should 表示义务，意为“应该”或“应当”。 E.g You should do what your parents tell you. He should look
2、for a job, but he doesnt want to. How should I know? I suggest that you should stay here till your teacher comes.,Should （考点1）,should 用于完成时中的肯定句，表示应完成而未完成的动作。 E.g,1.He looks so ill. He should have stayed at home. should 用于完成时中的否定句，表示不应完成但已做的动作。 E.g, 1. They shouldnt have left the classroom.,1. With
3、so much work on hand, you _to see the game last night. ( )mustnt go B shouldnt go C.could have gone D.shouldnt have gone,should 标推测时，暗含可能性很大。 The film should be very good because it has first-class actors. should 可用在某些从句中，表虚拟语气。 I suggest that you (should) obey the rules in your new company. I advis
4、e that you finish your homework without any help from your classmates.,Should （考点2）,ought to,ought to 用于表示“想必会“(语气较must 弱)： 1. They ought to be there by now. 他们想必已到那儿了。 2. He ought to stop smoking. 他最好不要抽烟了。多数情况下，ought to可与should互换使用。 Ought to的反意疑问句用shouldnt替代。,13. You ought to have helped him with
5、his English, _ you ?A. wont you B. ought not you C. shouldnt you D. wouldnt you,比较had better, should & ought to,三者均表示建议，意为“应该”，“应当”或“最好做”.三者的语气程度为渐强。 Had better指一般性的建议，最弱。 Should&ought to含义相近，常可互换。区别在于，ought to常指特殊情况下的“应当”。Should则指一般情况。见下页例句。,You ought to help him because he is in trouble now.(语气强，有
6、命令意味。) You should have a rest after finishing your sports.（一般性建议） You ought to call the police when you find something wrong in your house. He should take care of the babies tonight.,mustcan/couldmay/might,Modal Verbs 2,must 1. 表示义务，意为“必须”。（主观意志）We must do everything step by step.Being a student, yo
7、u must try your best to pass the exams.You are an adult, you must take the responsibilities to your behaviors. I must go now as my boyfriend is waiting for me outside.,Must,-Must we hand in our homework now?-No, you neednt./ No, you dont have to.对must的问句，肯定回答用must或have to而否定回答一般不用mustnt，因为mustnt表示禁止
8、，用neednt或dont have to，意思是“不必”。In the classroom, you must not smoke. -Must I leave now?-No, you neednt./No, you dont have to.,must （考点1）,2 must 表示推断或揣测。意为“想必，一定，准是。” 且只用于肯定句。 He must be ill, because he looks so pale. You must be tired after your long walking. Look! He is driving such a good car, he m
9、ust have earned a large amount of money abroad. It must have rained last night, for the ground is wet.,must （考点2）,Have to,have to 表示客观需要去做的事情，意为“必须，不得不。”I have to get the station early to catch the first train. We missed the bus so we had to walk home. We have to overcome all kinds of difficulties.,
10、Have to 有多种时态。常见的有：一般将来时， We will have to gather at the school gate at 7 tomorrow. 一般现在时 I have to take more money with me because my gf has so much to buy. 一般过去时 Finally, we had to give up our idea to hold a picnic outside as it rained for a whole afternoon.,Have to （考点）,must表主观意志，而have to表由于客观因素不得
11、不做完成的事情。 Must没有过去式，除在间接引语中可表示过去的时间。在直接引语中表示过去的时间用had to代替。 I told her that she must give up smoking. She said, “We had to get everything ready that night.”,比较must & have to,情态动词must,can/could,may/might 表推测,1 肯定句中用must（一定，很可能），may（可能），could/might（也许，或许） 语气程度依次减弱，即，must为十分肯定，may把握不大，might/could可能性很小。
12、Ps：might/could并非过去时态，只是语气较委婉，或因说话者认为可能性小而不敢肯定的一种手法。,推测modal verbs （考点1）,肯定句中对当前行为，状态的推测句型。 must/may/could+do/be He must come from Africa. 肯定句中对此时此刻正在进行动作的推测。 must/may/could+be doing The student may be still waiting for his teacher in the office. 肯定句中对过去发生的事情的推测。 must/may/could+have done They may hav
13、e finished the work yesterday, because I saw them shopping in the supermarket.,在否定句中用can not/ could not 或may not/might not表推测 Its snowing outside. He cant be on the playground. The classroom cant have been cleaned by Tom, because I saw him playing football at that time yesterday.,推测modal verbs （考点2）
14、,在疑问句中，常用can表示“可能”。Who can it be?How can he solve such a hard work?I lost touch with him for many years, where can you find his address?,推测modal verbs （考点3）,推测modal verbs （考点4）,He must be reading, isnt he? You must do it yourself, dont you? He may have gone over the article, hasnt he? It may have ra
15、ined last night, didnt it,canbe able to,Modal Verbs 3,can & be able to 同与异, 二者表示能力，泛指能力(具有知识、技巧、本领而能读书、游泳、说英语，踢足球等) I could / was able to swim well when I was only ten. 如果指过去具体某时或某个场合能(设法)做到某事succeeded in doing sth./managed to do sth.),在否定句中两者都可用, We had a holiday yesterday, but couldnt / werent abl
16、e to go to the seaside. 在肯定陈述句和疑问句中,只能用be able to. He didnt agree with me at first, but I was able to persuade him.How many children was he able to save from the flood?,shallneeddarewill/would/used to,Modal Verbs 4,1）用于第一人称表将来。I shall go to work after I have finished school. 2）用于一、三人称疑问句、表征求对方意见或向对方
17、请求。 Shall he come in? Come in, please. 3）用于二、三人称肯定句，表示保证、承诺、威胁、警告。 You shall be punished if you insist on doing it this way.,Shall 的考点,Need 情态动词与实义动词比较,need “必需” “需要” ; - Must I be here before 9 oclock ?- No, you neednt. (不能说: No, you mustnt.)- Need I be here before 9 oclock?- Yes, you must. (不能说: Y
18、es, you need.) 注意: 1) need作情态动词, 不能用于肯定陈述句, 在陈述句中,应该用need的实义动词表达.You need to be here before 9 oclock.(不能说: You need be here before 9 oclock.)2) 回答Must/Need开头的问句, 不能说:Yes, you need./No, you mustnt.,dare (过去式 dared) “敢于”,He dare not go into the building even in the daytime. How dare you ask me such a
19、question? If you dare say that again, you shall be punished. 注意: dare作情态动词时,不能用于肯定陈述句中(if条件句除外). 在肯定陈述句中, 要用dare的实义动词来表达 “敢于”.在实义动词dare的否定句中,可以省去后面的to.,不能说: He dare go into the building in the dark night. 正确： He dares to go into the building in the dark night. 正确： He doesnt dare (to ) tell us the tr
20、uth.,dare (过去式 dared) “敢于”,表示习惯性动作或状态,will 指现在 “往往” 、“总是” 、“就会” Fish will die out of water. Hell talk for hours if you give the chance. would 指过去 “常常” “总是” (对现在没有暗示)比较: used to 指过去 “常常” “总是” (暗示现在不再如此) She would / used to stand and talk with her neighbors in front of the house as she had breakfast.,
21、will (过去式would)用于各种人称,表示意愿,意志.,I will stick to my plan though all of you are against it.I told him to give up smoking, but he wouldnt listen.,情态动词 + 完成式动词 (指过去的动作或情况),may / might have done sth. 可能做过(了)某事 cant / couldnt have done sth. 不可能做了某事 must have done sth. 准是做了某事 neednt have done sth. 本不必做某事(实际
22、上已做) could have done sth. 本可以做某事 (实际上没做) should have done sth. 本应做某事 (实际上没做) ought to have done sth. 本应做某事 (实际上没做) shouldnt have done sth.本不应做某事 (实际上已做) oughtnt to have done sth. 本不应做某事 (实际上已做),1、了解情态动词的完成式用法,（一）should /ought to have done本来应做而未做，表达遗憾感情色彩,例1：I told Sally how to get there,but perhaps
23、I _for her.(NMET94)had to write it out must have written it out C. should have written it out D. ought to write it out,例2： I was really anxious about you, you_home without a word.(NMET2001)A. mustnt leave B. shouldnt have left C. couldnt have left D. neednt leave,（二）may/might have done可能已做 must have
24、 done 一定已做 cant have done不可能做,例1：-Where is my pen?- I _it.(NMET88)A. might lose B. wouldnt have lost C. should have lost D. must have lost,例2： The light in his room is still on, so he _ to bed. A. mustnt have gone B. must have gone C. shouldnt have gone D. cant have gone,析：选D。由于他房间里的灯还亮着推测，他不可能已经上床睡
25、觉了，应填cant have gone 。,(三）could have done指本来能做而实际未做，表达遗憾的感情色彩,You could at least have sent five cards.你至少可以寄5张明信片的。,2、熟悉情态动词委婉用法：could, would, might等情态动词均有委婉用法，它们不是过去式而是表示语气委婉、客气、礼貌，常用与疑问句，并多用于习惯表达， 如would you please, would you mind, would you like to等，might还可以用于肯定句表示推测，表示可能性小， might和could表示征求对方意见时，回
26、答必须还成may, can.,例1：-Could I borrow your dictionary?Yes, of course you_. A. might B. will C. can D. should,析：选C。该句用can的委婉表达式could 来征求对方意见，could 和might通用，但回答时必须还成can或may，因此该题不选A.,例2：_you mind my smoking here? A. Should B Could C. Might D. Would,析：选D。征求对方意见我是否在这儿吸烟，语气理应委婉，所以应选委婉的表达方式would you mind来征求对方意
27、见。,3、弄清情态动词的异化现象,有些情态用于疑问句进行回答时，出现了异化现象，此时回答在某 个角度不能继续使用该情态动词， 而改用别的动词。,例1：-Must I start at once? No, you_. A. neednt B. mustnt C. cant D. wont,析：A。由语境可知该答句表示“不必”，而mustnt表示“不准、禁止”，不符合语境，显然应使用neednt表示“不必”，但肯定句回答继续用must。,例2：-Need I hand in my exercise book at once? Yes, you_. A. must B. need C. can D.
28、 will,析：选A。根据规定need用于一般疑问句作肯定回答应换成must,而作否定回答时，使用need的否定式neednt。,4、掌握征求意见情态动词的回答,不少情态动词可用于疑问句征求对方意见，但人称上有时有特殊要求，请看下表：,例1：-_I tell John about it? -No, you neednt. I have told him already.(NMET94) A. Shall B. Will C. Can D. May,析：选A。从回答句“No, you neednt”的语境可知，问句征求对方意见，表示“需要”而且用语第一人称，要使用shall。,例2：_you p
29、lease help me with my English? A. Would B. Do C. Shall D. Can,析：A。次句表示追求对方意见，有“愿意 ”之意，而且又用于地二人称，应选用would。,1、情态动词可表示某一特定的语气或态度：, can表示惊异、怀疑、不相信的态度（用于否定句、疑问句或感叹句）How can you be so careless? may可以表示祈使句，表示祝愿。May we never forget each other. Why/How should结构表示说话人对某事不理解、感到意外、等意思，常译为“竞会”。How should I know?,
30、5、注意下列细节：,2、shall用于第二、三人称陈述句中，表示说话人给对方的命令、警告、许诺或威胁。You shall have the book when I finish it. 3、cannottoo/enough表示“无论如何、也不过分” “越、越好”: You cannot be too careful. 4、cannot but+do sth.表示“不得不，只好”： I could not but choose to go. 5、may well/may as well. 前者为“完全能、很可能”=to be likely to He may well be proud of his son.后者为“最好，满可以”=had better You may as well stay here over the night. 注意区分情态动词否定式表达含义：或许不may not; might not 不可能cant 不能够cant 不许可may not; cant;mustnt 不必neednt 不应该shouldnt; oughtnt to,
