情态动词和虚拟语气 情态动词,and,虚拟语气

　　[摘要] 在学生学习英语的过程中，情态动词和虚拟语气这一大块是掌握和应用的一个难点，为帮助同学们拨开迷雾，找到攻克该难点的有效方法，本文给出详尽的讲解并富有经典例句。
　　[关键词] 情态动词 人称 语气
　　
　　平时练习甚至高考中常把情态动词和虚拟语气放一起来考察，为帮助同学们正确区分相似点，现将该模块总结如下：
　　一、情态动词
　　有一定的词意，但词意不完整，不能独立使用，和后面动词原形一起构成谓语，常无人称和数的变化。
　　1.had better
　　（1）后接不带to 的动词不定式，翻译成“最好”You had better not go home.
　　注：You had better…用于同辈或晚辈，不用于对长辈。
　　（2）had better have done…表与过去事实相反的假设或愿望，该点归于虚拟语气一节。
　　I had better have bought a larger coat.
　　2.should, ought to
　　（1）翻译成“应该”，两者同义，但ought to口气稍重些。You should go to class right away.
　　（2）表推测，常是对现在或未来的推测，翻译成“应该…了吧”
　　The famous writer has just finished his latest novel and the book should be published in a month or so.If we work now, we ought to finish it before lunch.
　　（3）表达责备、遗憾、后悔等语气的情况，这点属虚拟语气。
　　｛should/ought to have done…表过去本应做而实际上未做
　　｛shouldn’t/oughtn’t to have done…表过去本不该做而实际上却做了
　　You should/ought to have come earlier, but you didn’t.
　　You oughtn’t to have left home without a word.
　　注：He should have finished the work by now. 表推测，归于上一条。
　　（4）should 用于第一人称表征求意见。Should I open the door? （不用ought to）
　　（5）should 用在肯定句中表惊讶等感情色彩，翻译成“竟然”或以how 、why开头的句子。You can’t imagine that a well-behaved gentleman should be so rude to the lady.
　　3.must
　　（1）表说话人主观上的看法，表义务或强制，语气最强烈。翻译成“必须”。
　　You must use your heart to learn English well.
　　（2）表必然性。翻译成“会、能”。 Given enough time, he must finish it.
　　（3）用于疑问句，表询问对方的意愿。
　　----Must we hand in our exercise books today?----Yes, you must.
　　----No, you don’t have to ( you needn’t ). 注：否定回答不用mustn’t，它表禁止。
　　（4）用于肯定句中，表有把握的猜测或假设。翻译成“一定是”。
　　｛对现在或未来情况的肯定推测：must do （否定can’t/couldn’t do ）
　　｛对现在正在进行状态的推测：must be doing （否定can’t/couldn’t be doing ）
　　｛对过去已发生情况的推测：must have done （否定can’t/couldn’t have done ）
　　Judging by his accent, he must be from the south.
　　Tom bought a lot of apples, he must like eating apples.
　　----Where is Tom?----He must be studying in the classroom.
　　----Where is Tom?----He must have been to Shanghai.
　　4.have to
　　（1）强调客观需要，或外界环境、情况的制约。翻译成“不得不”。有时态之变。
　　I had to work when I was at your age. I will have to buy a house.
　　（2）否定： not have to do=needn’t do.
　　You don’t have to buy a house at present, for it is too expensive.
　　5.can, could
　　（1）表体力、脑力、技能方面的能力。He can drive but he can’t ride a bike.
　　can 表能力时，可用be able to 代替。She was able to swim before.
　　但“设法成功做成某事”，用be able to （结果上能够），不用can/could（理论上可以，不涉及结果）。The big fire spread fast, but everyone was able to get out.
　　（2）can表客观可能性。Man cannot live without air.Children can be very naughty.
　　（3）can表请求和允许。
　　----Can I go now?----Yes, you can. I’m going away. You can have my seat.
　　could也可表请求，语气较委婉，用于疑问句，答语用can.
　　----Could I come to see you tomorrow?----Yes, you can.(否定No, I’m afraid not.)
　　（4）can 还可用于疑问句、否定句和感叹句中，表说话人惊异、怀疑的态度。
　　Can this be true? How can you be so careless?
　　（5）can/could 表推测或假设。
　　｛对现在或将来的推测：can/could do (否定can’t/couldn’t do)
　　｛对过去的推测或假设（虚拟）can/could have done (否定can’t/couldn’t have done)
　　本来可以做而实际上未做。
　　He can’t be at his fifties. We can have started early, but we didn’t.
　　You could have asked him for advice, but you didn’t.（假设）
　　Just now I met her in the street, so she can’t have been to HongKong.（推测）
　　6.may, might
　　（1）表许可、允许。
　　You may stand as long as you like. （可用can）
　　She said her daughter might have a vocation.
　　（2）表请求，might比may语气更委婉。否定回答可用can’t或mustn’t，表“不可以” 、“禁止”之意。
　　----Might I use your book?----No, you mustn’t.
　　----May I take this book out?----Yes, you can./No, you can’t/mustn’t.
　　注：用May I…?征询对方许可，文体上较正式，口气上较客气。现代口语中，用Can I……?征询对方意见更常见。
　　（3）表可能发生，翻译成“或许”。I may/might visit your parents tonight.
　　（4）常用在肯定句中，表推测、可能。 ｛现在或将来：may/might do
　　｛现在正在进行：may/might be doing ｛过去已发生：may/might have done
　　He may be late for the bus. He may be running home now. He might have read the book.
　　（5）may/might as well do 用于第一人称翻译成“我最好还是”；用于二三人称，表说话者的建议，翻译成“不妨”。I might as well go out quietly.
　　（6）may用于祈使句表祝愿。may必须置于句首。（虚拟语气）May you succeed!
　　7.need
　　（1）做情态动词时，仅用在否定或疑问句中，翻译成“需要”。
　　----Need (=must) I finish the work today?----Yes, you must.----No, you needn’t.
　　You needn’t be polite to him.
　　（2）needn’t have done 对过去的假设，表本来不必做而实际上却做了。
　　You needn’t have watered the flowers, for it is going to rain.
　　注：need 也常用做实义动词，有时态、人称和数的变化。
　　 He needs to finish the work tonight.
　　 The work needs to be finished tonight. The work needs finishing.
　　8.dare
　　做情态动词时，主要用于疑问句、否定句和条件从句中。翻译成“敢于”。
　　Dare you go out in dark? He daren’t speak English before such a crowd, dare he?
　　注：做实义动词：在肯定句中，后常接带to的不定式；在否定和疑问句中，接带to或不带to的不定式。I dare to swim across the river. He does not dare (not) answer.
　　Do you dare (to) disobey your teacher?
　　9.shall
　　（1）用于第一或第三人称的疑问句中，表征求对方的意见或向对方请求。
　　What shall we do this evening?
　　（2）用于第二或第三人称，表说话人给对方的命令、警告、允诺或威胁。
　　You shall fail if you don’t work harder.
　　If you listen to me carefully, I shall give you some candy.
　　（3）表常规或决心。Nothing shall stop the wheels of history.
　　（4）用于法律规定。The law shall come into effect on May 1st.
　　10.will, would
　　will
　　（1）表无时间限制的习惯性动作，如真理、自然现象等，翻译成“总是，惯于”。
　　Fish will die out of water.
　　（2）表意志、意愿或决心。I will do my best to help you.
　　（3）表主张，won’t表拒绝。The car won’t start.
　　（4）用于第二人称，在疑问句中表请求、询问。Will you have a rest?
　　（5）will have done表推测，主要用于二三人称，表对已完成动作或事态的推测。
　　He will have arrived by now.
　　would
　　（1）表请求、建议，would比 will 委婉客气。Would you pass me the book?
　　（2）表过去反复发生的动作或某种倾向。表过去习惯动作时比used to正式，且没有“现已无此习惯”之义。后常跟动态性动词。During the vocation he would visit me every week.
　　（3）表估计或猜想。
　　｛过去一般情况：would doIt would be about 10 when he left home.
　　｛过去正在进行：would be doing What would she be doing there?
　　｛过去已发生：would have done I thought he would have told you all about it.
　　11.used to
　　（1）表过去习惯性动作或状态，但现已不复存在。后跟动态性或静态性动词。
　　Every night he used to teach me English.
　　（2）在疑问句，否定句，否定疑问句或强调句中，有两种形式。
　　疑问句：｛Used you to go to the same school as your brother?
　　｛Did you use to go to the same school as your brother?
　　否定句: ｛I usedn’t to go there.｛I didn’t use to go there.
　　否定疑问句: ｛Usen’t you to be interested in it?｛Didn’t you use to be interested in it?
　　强调句: ｛I certainly used to smoke, but it was a long time ago.
　　｛I certainly did use to smoke, but it was a long time ago.
　　（3）反意疑问句或简略回答，也有两种形式。
　　She used to be very fat, ｛use(d)n’t she? ｛didn’t she?
　　----Used you to get up early in the morning?----Yes, I used to./Yes, I did.
　　----Did you use to play chess?----Yes, I did.
　　would rather
　　（4）翻译成“宁愿”。
　　｛指现在或将来：would rather doI’d rather do it at once.
　　｛指过去：would rather have doneI’d rather not have told her the news.
　　（5）表选择，后接than。宁愿做…而不做…｛would rather do…than do…｛would do…rather than do…
　　I would rather stay at home than go out.I would stay at home rather than go out.
　　（6）后接从句用虚拟语气。
　　｛指现在从句用过去时：I would rather you paid me now.
　　｛指将来从句用过去时：I would rather you came tomorrow.
　　｛指过去从句用过去完成时：I would rather she hadn’t done that.
　　二、虚拟语气
　　表说话人的愿望、假设、猜测或建议，而不表客观存在的事实。通过谓语动词的特殊形式来表示。
　　1.用于条件状语从句
　　（1）虚拟情况：
　　①与现在事实相反：If I were you, I should stay at home.
　　②与过去事实相反：If you had come yesterday, you would have met him.
　　③与将来事实相反：If it should rain, the crop would be saved.
　　(1) 当条件句表示的行为和主句发生的时间不一致时，动词的形式要根据它所表示的时间来调整。
　　If you had followed the doctor’s advice, you would be quite all right now.（从句说的是过去，主句指的是现在。）
　　（2）以上可转换成下列形式：
　　①从句省略，用倒装句式“were/had/should+主语”。
　　Were I in school again, I would work harder.
　　Had you been here earlier, you would have seen him.
　　Should there be a meeting tomorrow, I would come.
　　②可用介词短语或句子来代替条件句。Without air, there would be no living things.
　　I would not have succeeded but for your help.
　　I would not have succeeded but that there hadn’t been your help.
　　2. 用于宾语从句
　　（1）wish+宾语从句 表不能实现的愿望，翻译成 “悔不该”，“但愿”等。
　　｛表现在不能实现的愿望，从句谓语动词用过去试；
　　｛表将来不能实现的愿望，从句用would/could+动词原形；
　　｛表过去不能实现的愿望，从句用had done或would/could+have done。
　　I wish we could go to the seaside today.
　　We wish we had arrived there two hours earlier. I wish you would do that tomorrow.
　　（2）在动词suggest, order, require, insist, desire, demand, arrange, command, propose, request等后的宾语从句中，用(should+)动词原形。
　　I suggested that the meeting (should) be put off.
　　注：上句中suggest意为“建议”；当意为“表明”时，从句中不用虚拟语气。如：
　　His pale face suggested that he was angry.
　　I insisted that you (should) give me my money back.
　　注：上句中insist意为“坚持（应该）”， 当意为“力言，强调”时， 从句中不用虚拟语气。如：Mike insisted that he had never stolen anything.
　　（3）用于表语从句，同位语从句。
　　做advice, suggestion, idea, order, plan, demand, proposal, request等名词的表语从句和同位语从句，谓语动词用 (should+)动词原形。
　　We all agreed to his suggestion that we (should) go to Beijing for sightseeing.
　　（4）在表语从句或状语从句中。
　　｛表与现在事实相反，谓语动词用一般过去时；
　　｛表与过去事实相反，谓语动词用had done；
　　｛表与将来事实相反，谓语动词用would/might/could+动词原形。
　　He looked at me as if I were mad. It looks as if it might rain.
　　He speaks English so fluently as if he had studied English in England.
　　注：as if (as though)后的从句也常用陈述语气，因从句中情况是可能发生或被设想为真实的。It looks as if it’s going to rain.
　　（5）用于主语从句
　　在主语从句中，谓语动词用“(should+)动词原形”，表惊奇，惋惜，理应如此等。
　　It is necessary/important/natural/desirable/advisable/strange/…… that we (should) clean the room every day.
　　It was a pity/a shame/no wonder/…… that you (should) be so careless.
　　It will be desired/suggested/decided/ordered/requested/proposed/…… that she (should) finish her homework this afternoon.
　　注：对从句表示的事实情况，若说话人对事实惊奇，用虚拟语气；反之，用陈述语气。如：It is strange that he didn’t come yesterday.
　　（6）用于定语从句
　　用在 “It is (high) time (that) …”中，从句谓语动词用过去式(be用were)或“should+动词原形”(should不可省略)，意为“（现在）该…”。
　　It’s high time we were going. It’s time that we should do it at once.
　　（7）用于if only引导的感叹句
　　｛对现在情况：did (be 用were)If only I were a bird!
　　｛对过去情况：had done If only I had taken his advice!
　　（8）在 ① “If it were not for…”中，翻译成“若没有”， 表同现在事实相反的假设。If it were no for the rain, the crops should/would/might die.
　　②在 “If it had not been for……”中，翻译成 “若当时没有”，表同过去事实相反的假设。If it had not been for your timely help, I would have failed.
　　结语：通过以上分析和讲解，不难发现有的板块，情态动词和虚拟语气是融合在一起的，所以在掌握记忆相关内容时，要综合考虑相关的语法点，将各个点掌握扎实。