1、情态动词总结I 情态动词的特征：1. 本身有词义。2. 不能独立作谓语。2. 后接动词原形一起构成谓语。3. 不随人称和数的变化。II 情态动词各自的基本意义及用法：1. can 与could用法对比点can could1、表“能力”Can you lift this heavy box?I couldnt understand what he said at all.2、表“许可”You can use a different material instead.He said I could borrow his bike.3、“怀疑”No, no, it cant be true.What
2、 on earth can this mean?We thought the story could not be true. How could you be so careless?4、can与be able to 区别1. could代替 can，表示语气更为婉转。 Eg. Could I use your bike? Yes, you can2. can (能够)=be able to(仅表能力时)，但be able to 表示一番努力后，才能做得到，且有更多的时态。2.may与 might用法对比点maymight1表“询问”May I ?(=Can I ?)Might I ?(=C
3、ould I?)(但比用may 更客气)2.表“允许”You may take the boy there.He told me he might come. (might 与told相呼应)3表“可能”“或许”She may nor like this place.Im afraid he might not like this play.注：1. May I?的答语。2. may可表示期望或祝愿 May you succeed !3. may (might) 用于目的状语从句。肯定：Yes, you may.否定：No, you mustnt 不行 （语气强硬）No, you may no
4、t 或No, youd better not.The emperor gave them some gold in order that they might begin their work at once.3. must与have to用法对比点musthave to1. 表“必须”（主观看法）必须；没有过去式，可用于间接引语中。He told me I must do according to what he said.（客观需要）不得不，有多种时态。Its raining heavily, we cant go now.2. 疑问句Must I ? Yes, you must.（一定）
5、No, you neednt./ you dont have to.(不必)Do you have to go today?Yes, we do.You dont have to worry about that.4. need与dare用法对比点needdare1.情态v.+动词原形 1）否定式 2）疑问式 He need not (neednt)go.-Need we do it again?-No, you neednt do it again.He dare not say so.Dare she go out alone at night?How dare you say Im un
6、fair?If he dare do that, hell be punished.I dare say. (固定用法)2.实义v. +to do 1）肯定式 2）否定式 3）疑问式He needs to go.He doesnt (does not) need to go.Does he need to do it again?No, he doesnt need ot do it again.He dares to say.He does not(doesnt)dare to say.If you dare to jump into the water from here, so dare
7、 I .3. did not need to do表示过去没必要做She didnt need to attend the meeting yesterday, and she stayed with her children.(她没有参加)5. should与ought to用法对比点shouldought to1、表“应该”表劝告、建议You should listen to the doctors advice.We should learn from Zhang Hua.“有责任有必要”做某事You ought to finish your work before you go hom
8、e.We ought to help each other.2、表“估计”They should get home by now.“非常可能”的事，可译为“总应该”If we start to work right now, we ought to finish it before lunch. 注：1）should还可在虚拟语气中的使用2) 注意：ought to的疑问式及否定式-Ought he to go? -Yes, I think he ought to. -No, he oughtnt to. 否定式：oughtnt to do (不说ought to not do) 反疑问句：o
9、ughtnt _?6. shall与will用法shallwill1. 征询对方意见或请求指示，用于第一、三人称：Shall I (we)? Shall he (she)? Where shall I (we)wait for you?1. 询问对方的意思或向对方提出要求：Will you (please)? Wont you?Would you like to.? (would替代will更客气)Wont you go and see the film?你不去看电影吗-Yes, I think I will. 不， 我想去。2. 表示说话人的“意愿”有“命令”“警告”“强制”“允诺”“决心”
10、等，用于第二、三人称。You shall do what I tell you ( to do).我叫你干什么你就干什么。Everything shall be done to save the ship.一定要竭尽全力来拯救这艘船。2. 表示“意志”“意愿”，用于各种人称：I wont do anything you dont like.我不会做任何你不喜欢的事。Would表示过去时间的“意志”“意愿”Shylock would not take the money earlier.夏洛克先前是不肯要钱的。7. used to与would用法used towould1.表示过去的动作、状态，
11、重在与现在情况的对比，不一定要有时间状语。I used to play cards a lot, but now I seldom play.My hometown is not what it used to be.1.只表示过去动作的重复，有明确的时间状语。I would go to see my grandfather on Sunday when I was in the middle school.2.would 后只接表动作的动词，不接表认识或状态动词He used to be nervous in the exam.2. 表示过去的习惯有时可互换：When we were ver
12、y young, we used to / would go skating every winter.3. 表示过去的次数时，不能使用：( ）We went to the Great Wall five times when we were young.( X ) We used to go / would go to the Great Wall five times when we were young.注：used to do的否定式：usednt to do 或didnt use to do (usednt也可写作usent)疑问式： Did you use to do ? Didn
13、t you use to do? Used you to do? Usednt you to do?II 情态动词表推测：1. 大多数情态动词（除表能力、许可、意志外），都可以表示推测，其程度有差异。按可能性程度的高低排列为：must will would ought to should 完全肯定 完全可能 很可能 can could may might 可能 有可能2. 区分情态动词的否定含义：may not或许不、可能不 might not可能不 cant 不可能mustnt不许、禁止 shouldnt不应该 neednt 不必3. 情态动词表推测具体运用：情态动词可以对现在、进行、过去推
14、测。S主+情态动词 + be + adj对“性质”“特征”的推测S主+情态动词 + be + n对“职业”“事物”的推测S主+情态动词 + 动词原形对经常性行为的推测S主+情态动词 + be + V-ing对进行着的行为的推测S主+情态动词 + have + PP对过去的行为的推测情态动词表推测时：1、can只能用于否定句和疑问句2、must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）3、如句中有情态动词 + 完成时，定是对过去的推测 。4、句中如有表示不肯定的话语E.g I am not sure; I dont know 之类，常选may /might的各种形式。4. 表示反劝的特殊的表推测形式1). could + have + P.P.表示本来能做到，但事实上没有做到。He could have finished the task on time, but the heavy snow came.2) . couldnt +have + P.P.表示本来不能做到，但已经做到了。She could not have covered the w
