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1、人教课标版 高一 必修 3情态动词的语法特征1) 情态动词 不能单独做谓语, 除ought 和 have 外, 后面只能接不带to 的不定式。 2) 情态动词没有人称, 数的变化, 但有些情 态动词, 如can、will也有一般式和过去式的 变化。 3) 情态动词的“时态”形式并不是时间区别的 主要标志, 不少情况下, 情态动词的现在式形 式和过去式形式都可用来表示现在时间、过 去时间和将来时间。1) can的主要用法是：A. 表能力： eg. The girl can dance very well. B. 表可能性: eg. Can the news be true?C. 表示请求或允许:
2、eg. Can I sit here? can 和could：2) could的主要用法是：A. could 是can的过去式, 表示与过去 有关的能力和推测: eg. We all knew that the young man couldnt be a doctor.B. could可以代替can表示请求, 但语气较can客气、委婉:eg. Could you lend me your dictionary? Could I use your bike?3) can和could接动词的完成形式，表 示可能已经做某事。can用在否定和疑 问句中, 表示不相信、怀疑等态度。eg. They c
3、ant have gone out because the light is still on.may 和might ：may 常用来表示： A. 表示请求、允许;比can较为正式: eg. May I come in ? You may go now.B. 表示说话人的猜测: “也许” “可能”: 通常只用于肯定句和否定句中。eg. -I believe the man is from England. -But I may be wrong. The guest may arrive this afternoon. 在肯定句中，may 的可能性比can 高，may 表示现实的可能性，can
4、 表示理论上的可能性。如：The road may be blocked. 这条路可能不通了。 The road can be blocked. 这条路可能会是不通的。 在疑问句中，表示可能性用can。如：Where can he be? 他会在哪呢？C. 表示祝愿;但语气较正式: eg. May you succeed! May you have a good journey! might 的用法有:多在间接引语中表示过去的可能和 允许。如: She said that he might take her bike. 她说他可以拿她的自行车去用。除了在间接引语中以外，might 一般不表示过
5、去的可能或者许可。如要表示 过去的可能可以用could, 表示过去的许可可以用was( were) allowed to 或者 had permission to 。表示现在的可能，其可能性要比 may 小。如：She might go home tomorrow.说不定他明天会回家。表示现在的许可, 语气比may 较委婉, 一般用于疑问句(包括间接疑问句), 不可用于肯定句或者否定句。如: Might I have a word with you? 我可以和你说句话吗？will和would：1. will是助动词或是情态动词？ will用于构成将来时是助动词。用于 表示“意志”“决心”“请求
6、”是情态动词。 would亦同理。 eg. I will tell you something important.我要告诉你一些重要的事。（助动词） Will you tell her that Im here? 请您告诉她说我在这儿，好吗？（情态动词） 2. 在疑问句中用于第二人称，提出请求或询问。 eg: If you want help - let me know, will you? 如果你需要帮助, 让我知道, 好吗? Will you type this, please? 请打印这个, 好吗？ Wont you sit down? 请坐下, 好吗？ 3. would比will客气
7、委婉。 eg: Would you help us, please? 请您帮助我们，好吗？ （表请求）Id go there with you. 我要和你一块到那儿去。 Teacher wouldnt allow it. 老师不会允许这件事。（表意愿）（表许可）shall和should：1. shall用于构成将来时是助动词。shall用于征求对方的意见，表示 “决 心” 是情态动词。 eg: Perhaps I shall pay a visit to England this winter.可能今年冬天我会去英国观光。 （构成一般将来时, 助动词）Shall we go by train,
8、 Mom?妈妈，我们乘火车去好吗？（用于征求对方的意见，情态动词） I shall go at once.我必须立即去。（表 “决心”，情态动词） 2. should表示义务、建议、劝告，意为 “应该”。 “should+ have+过去分词”表示本应该在过去做但没有做。eg: You should keep your promise. 你应该遵守诺言。She should have passed the exam. 她应该通过考试的。must和 have to 1.must用于一般问句中,肯定回答用must 否定式用 neednt或dont have to，做 “ 不必”,mustnt表示“
9、禁止，不允许” Must I finish all assignments at a time? Yes, you must.No, you neednt. I dont like this TV set. We must buy a new one. There was no more bus. They had to walk home.2.表示“必须”这个意思时，must 和have to 稍有区别。must着重说明主观看法，have to 强调客观需要。另外，have to 能用于更多时态。 You must be the new teacher. He must be joking.
10、 There is nobody here. They must have all gone home. 3.must表示对某人某事的猜测, 作“准是 ”, “一定” , 一般用于肯定句中。对过去 发生的事情作肯定判断用must have done He must come and worry her with question, just when she was busy cooking the dinner. Of course，after I gave her my advice，she must go and do the opposite.4. must表示“偏要, 硬要”, 指做
11、令人不快的事情Modal verbsa. should, ought to都可表示“应该”。ought to用于表示按道理应当，常指客观的义务或责任，大多数情况下可用 should代替，但比should语气重。I should help her because she is in trouble. You ought to take care of the baby.b. 表示劝告、建议或命令时，should和ought to可通用，但在疑问句中常用should。ought to的否定式为oughtnt to或ought not to。You should / ought to go to c
12、lass right away.Should I open the window?What should we do next?c. should, ought to都可表示推测。He ought to / should be home by now. This is where the oil ought to / should be. 3. must和needa. need作情态动词时, 只能用于疑问句和否定句。构成否定句和疑问句时不借 助于助动词do。Need I finish the work today?Yes, you must. / No, you neednt.b. must的
13、肯定形式表示“必须”，否定式表示“禁止、严禁”。You must come here. You mustnt take the book away from the library. 2. A: _ Xiao Feng find the origin of Easter from that book?B: No, he _.1. A: _ you like to go to a special event with us on Saturday?B: Yes, I _ _.Wouldd like to go with you on SaturdayCouldcouldnt find itExe
14、rcise 3. A: _ I go with my friend to the harvest festival?B: Yes, you _ _.4. A: If I want to be a doctor _ I study science?B: Yes, you _. should study scienceMaymay go ( with your shouldfriends )5. A: He is very handsome. _ he play the role of the prince?B: No, he _ _. cant play the role of theCanpr
15、ince6. A: The neighbour s children are older this year. _ they stop playing tricks at Halloween?B: Perhaps, they _ _._.Mightor Shouldmight stopor should stop playing tricksplaying tricks at Halloweenat Halloween1. -_ I go out to play, mum?-No, you_. You should do your homework first.A. Might; wouldntB. May; had better notC. M
