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1、高考语法专题复习之情态动词与虚拟语气 许昌县三高【知识梳理】高考常考考点：1. 情态动词本身所表达的意义，如表示禁止、命令、威胁、许诺等意义；may, might, need, should等的用法。2. “情态动词+have done”表示推测。3. 情态动词后面省略形式的用法区别，如：could (do），could have (done)的区别。4. 虚拟语气中的含蓄条件句以及宾语从句。5. 判断陈述语气与虚拟语气。一、情态动词(一) 情态动词的基本用法1. can be able to couldcan和be able to都表示能力，意思上没多大区别。但can只有现在和过去时，而be
2、 able to则有更多的形式。但当成功地完成某一具体动作时，通常不用could而用was/were able to来表示。这时was/were able to 相当于managed to，表示经过一番努力，终于能够完成某事。如：The wounded man still was able to get to the village and was saved in the end.can和could: can和could都可以表示能力、技能、许可、建议或请求和可能性。但比较委婉客气地提出问题或陈述看法，一般用could，回答时则用can。如：Could you help me carry t
3、he bag?Can I help you?2. may/mightmay/might表示可能，但may比might可能性大。如：Why isnt he in class?He may be sick.(生病的可能性较大)He might be sick.(生病的可能性较小)may/might表示允许，may用于现在时或将来时，might常用在间接引语中表过去时，但might也可用于现在时间，表示比较委婉的语气，回答用may。如：He says we may leave.He said we might leave.may / might 表示建议或请求，但might比may 更客气，意思更肯
4、定而无过去时态的含义。如：-May / Might I use your bike? -Yes, you can / may. /-No, you mustnt3. must have tomust表示必须，应该，强调主观意愿，没有时态变化。must表示肯定的推测。如：The light is still on, so he must be at home.mustnt 表示禁止做某事。如：have to表示必须、不得不，是由于某种外界（客观）原因而必须，不得不做某事，也可表示经常的或习惯性的事必须做。have to的否定形式表示不必。have to可用于多种时态中。如：You will ha
5、ve to clean your own boots when you join the army.I have to be at my office every evening.4. should / ought toshould和ought to表示应当、应该，前者比后者语气轻。如：You should / ought to work hard.Since she is not here, he should / ought to be in the classroom.should/ought to的否定形式表示禁止之意。如：Children shouldnt smoke.should可
6、表示陈述意见，推出建议或请求；而ought to可以表示劝告之意。如：You ought to respect your parents.He suggested that they should leave at once.5. will / wouldwill 用于各种人称表示意志、意愿或决心等，否定式wont + 动词。如：I will tell you all about it./ Tom wont do such a thing.will用于疑问句中，常用在第二称时表示说话人向对方提出请求或询问如：Will you tell her the news when you see her
7、?will 表示习惯性的动作，有总是、惯于的含义。如：Fish will die out of water.would 表示客气的请求、建议或意愿。如：Would you please be quiet?Would you like coffee?would 表示过去反复发生的动作。如：When I passed my school，I would see my teachers who taught me 5 years ago.6. need: 作必要讲，既可作情态动词，也可作实义动词。作实义动词时后面的动词不定式要带to，其变化与一般动词相同。如：I need to think it o
8、ver.Need you go now? Yes, I must./No, I neednt 7. dare: 表示敢的意思。作为情态动词时，主要用在疑问句和否定句中。dare若作实义动词，后面可带to的不定式，此时to也可以省略。dare与need的用法相似。如：How dare you say that?She doesnt date(to)ask her father.8. used to: 表示过去常常发生的动作或存在的习惯，但现在已不复存在了。如：He used to smoke.9. shallshall作为情态动词用于第二、三人称，表示说话人的意愿，有命令、警告、威胁、强制和允许
9、等意思。如：We/You shall do as our teacher says.在疑问句中，shall用于征求对方的意见或请求指示，常用于第一、第三人称。如：Shall he go out for a walk?（二 ）、 情态动词表示推测或判断的用法1. 表肯定推测：1）对现在和未来的推测：must /may / might /could/should+动词原形2）对过去的推测must /may / might /could/should +have done2表否定推测：1）对现在和未来的推测：cant +动词原形2）对过去的推测 cant +have donecant只用于否定句、疑
10、问名（could可用于肯定句）。例如：It must have rained last night.She may not be at home. = It is possible that she is not at home.She cant be at home. = It is impossible that she is at home.They should be there right now.（三）情态动词表示责备的感情色彩，用法如下：1. should have done表示本来应该做某事而实际上未做，而shouldnt have done则表示本不应该做某事而实际上做了。如
11、：You should have told me about it earlier.You shouldnt have said such words to your parents.2. ought to have done 也表示本应该.，而ought not to have done则意为本不应该.。如：You ought to have told me about it earlier.You ought not to have said such words to your parents.3. neednt have done 表示本不必做某事而实际做了。如：You neednt
12、have walked so quickly since time was enough.4. could have done 表示本来能.而事实上未做到。如：I could have come on time, but my car broke on the way.二、虚拟语气：用于条件状语从句中1. 表示与现在事实相反的假设条件状语从句中的谓语动词：过去式（be动词的过去式用were），主句中的谓语动词:would/should/could/ might + 动词原形。如：If I were a boy, I would join the army.If she had time, sh
13、e should go with you.2表示与过去的事实相反条件状语从句中的谓语动词：过去完成时，主句中的谓语动词：would/should/ might / could + have +过去分词。如：If he had taken my advice, he would have succeeded in the competition.3 表示与将来事实相反条件状语从句中的谓语动词：一般过去时或should(were to) + 动词原形，主句中的谓语动词则用would / should/could might + 动词原形。如；If it were to rain tomorrow,
14、 the football match would be put off.4 错综条件句：当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，动词的形式要根据它所表示的时间作相应调整。如：If they had worked hard, they would be very tired.(从句说的是过去，主句指的是现在)5. 虚拟语气的省略：有时可省略if,句子则变成下列形式：Were / Had / Should +主语+。如：Were I a boy, I would join the army.Had he taken my advice, he would have succ
15、eeded.Were it not for the expense, I would go to Britain.三、虚拟语气用于名词性从句1. 虚拟语气在宾语从句中的运用。wish + 宾语从句表示不能实现的愿望，译为要是.就好了等。表示现在不能实现的愿望，从句中的谓语动词用一般过去时；表示将来不能实现的愿望，从句中的谓语动词用would/could + 动词原形；表示过去不能实现的愿望，从句中的谓语动词用had + 过去分词或could(should) + have + 过去分词。如：I wish it were spring all the year round.I wish I had known the answer.I wish I could fly like a bird.在表示
