英语北师大版一轮复习讲练：Part II 语法部分 专题11 情态动词和虚拟语气

　　专题十一　情态动词和虚拟语气

　　情态动词

　　一、定义

　　情态动词表示说话人对某一动作或状态的态度。

　　二、特点

　　1．有一定词义；

　　2．不受主语人称和数的变化影响；

　　3．与主要动词的原形(或称不带to的不定式)一起构成谓语(除ought to作固定词组看待)。

　　情态动词无人称和数的变化， 情态动词后面跟的动词需用原形，否定式构成是在情态动词后面加 “not”。 个别情态动词有现在式和过去式两种形式， 过去式用来表达更加客气， 委婉的语气， 时态性不强， 可用于过去，现在或将来。情态动词属非及物动词，故没有被动语态。

　　基本助动词与情态助动词最主要的区别之一是，基本助动词本身没有词义，而情态助动词则有自己的词义，能表示说话人对有关动作或状态的看法，或表示主观设想。

　　三、用法

　　1．can (could)

　　Everyone here can speak English. (表能力)

　　He can't / couldn't have seen her there. (表猜测)

　　He could have gone home. (表猜测)

　　Could / Can I use your pen?

　　Yes, of course you can. (表允许)

　　How can you be so careless? (表怀疑、惊异，主要用于否定、疑问句)

　　Can / Could you lend me a hand? (表委婉发表观点)

　　2．may (might)

　　You may take whatever you like.(表允许，证据更委婉)

　　注：在回答以may引起的问句时，多避免用这个词，而用其他方式，如Yes, please. / Certainly. / Please don't. / You'd better not. / No, you mustn't.等，以免显得太严谨或不客气。

　　They might be having a meeting, but I'm not sure. (表可能)

　　3．must

　　You must buy a ticket. (表义务，意为“必须”)

　　注：回答Must...? 引出的问句时，肯定回答用must; 否定回答不能用mustn't, 而要用needn't或don't have to。

　　—Must I finish my homework now?

　　—Yes, you must.(No, you needn't / don't have to.)

　　This must be Lucy's. (表猜测，意为“想必；准是；一定”等，用于肯定)

　　“must have ＋ 过去分词”表示“想必”之意，表示对过去的事情的推测。

　　4．shall

　　Shall I play soccer after supper?

　　May I play soccer after supper?

　　If you don't behave yourself, you shall be punished.

　　5．will

　　I will do anything for you. 我愿为你做任何事。 (表意愿，用于各种人称陈述句)

　　Will you give me a cigarette? Or I will tell the boss.(表请求，用于疑问句)

　　She will stand there sleeping for hours. (表示某种倾向或习惯性动作)

　　6．should

　　You shouldn't be so careless. (表义务，意为“应该”，用于各种人称)

　　They should have arrived in Beijing by this time. (表推测，意为“想必一定、照说应该、估计”等)

　　It is simply a miracle that rice should grow in such a place. (表示语气较强的意为“假设；万一；竟然”)

　　7．would

　　I said I would do anything for you. (表意愿)

　　Would you please tell me the way to the nearest bus stop? (表委婉地提出请求、建议或看法)

　　When he had a problem to solve, he would work at it until he found an answer. (表过去反复发生的动作或过去的一种倾向)

　　8．ought to

　　I really ought to phone my mother.(表义务，意为“应该”，口气比should稍重)

　　There's a fine sunset; it ought to be a fine day tomorrow. (表推测，暗含很大的可能，语气较弱)

　　9．used to

　　There used to be a building at the street corner, but it has been pulled down. (表示过去的习惯动作或状态，现在不再发生或不复存在)

　　I usedn't / didn't use to smoke. (否定式)

　　Used you (Did you use) to go to school on foot? (疑问式)

　　虚拟语气

　　一、定义

　　虚拟语气表示说话人的愿望、假设、猜测或建议，而不表示客观存在的事实。虚拟语气通过谓语动词的特殊形式来表示二、用法

　　1．虚拟语气用于非真实条件句中，一是在if条件状语从句中；二是在含蓄虚拟条件句中，通过with, without, but for和动词不定式短语等表示虚拟的条件或句中含有or, or else, otherwise, but等词语，暗示句子的某一部分(前句或后句)需用虚拟语气。。

　　  条件状语从句 主句

　　与过去事实相反 had ＋ 过去分词 should / would / could / might ＋ have ＋ 过去分词

　　与现在事实相反 一般过去时 (be用were) would / should / could / might ＋ 动词原形

　　与将来事实相反 一般过去时或(should / were to) ＋ 动词原形 would / should / could / might ＋ 动词原形

　　If I were you, I would go with them. 假若我是你，我就同他们去。

　　If it hadn't been for your assistance, we wouldn't have succeeded. ＝ But for your assistance, we wouldn't have succeeded. ＝ Without your assistance，we wouldn't have succeeded.要不是你的帮助，我们就不会成功了。

　　If I asked him, I'm sure he'd help us.如果我向他提出要求，肯定他会帮助我们。

　　注意：错综时间虚拟条件句，即条件从句与主句所指时间不一致，如从句指过去，而主句即指的是现在或将来，此时应根据具体的语境情况，结合上面提到的三种基本类型对时态作相应的调整。

　　If it had rained last night, the ground would be wet now. 要是昨晚下过雨的话，现在地面就会是湿的。

　　You would be much better now if you had taken my advice. 假若你当时听我的话，你现在就会好多了。

　　2．虚拟语气用于主要是表示命令、要求、建议的动词后的宾语从句中。常见动词：一个坚持：insist；两个命令：order, command；三个建议：advise, suggest, propose；五个要求：demand, require, request, desire，ask。这些动词后面的宾语从句要使用虚拟语气用法。即从句中的动词使用should ＋动词原形，或者将should省略。

　　Mr Johnson insisted that the problem worthy of attention (should) be discussed at the meeting. 约翰森先生坚持应该

　　在会议外讨论这个值得注意的问题。

　　He urged that they go to Europe. 他敦促他们到欧洲去。

　　He suggested that we should leave early. 他建议我们早点动身。

　　He ordered that it (should) be sent back. 他命令把它送回去。

　　注意：insist作“坚持说；强调”解时，宾语从句不用虚拟语气；只有当insist作“坚持(应该)”解时，宾语从句才用虚拟语气。

　　The stranger we caught insisted that he had never stolen anything. 我们抓住的那个陌生人坚持说他什么东西也没偷。

　　3．虚拟语气用于wish后的宾语从句中，表示不能实现的愿望，意为“可惜……；…… 就好了；悔不该……；但愿……”等。表示现在不能实现的愿望，从句的谓语动词用过去式；表示将来不能实现的愿望，用“would (could)＋动词原形”；表示过去不能实现的愿望，用“had ＋过去分词”或“(could) would have＋过去分词”。

　　She wished she had stayed at home. 她后悔的是她当时要是留在家里就好了。(与过去相反)

　　I wish you would go with us tomorrow.要是你明天同我们一起去就好了。(与将来相反)

　　I wish I were you. 我要是你就好了。(与现在相反)

　　4．虚拟语气用在would rather后的从句中。若与现在或将来事实不符，从句用一般过去时；若与过去事实不符，从句用过去完成时。

　　I would rather you paid me now. 我希望你现在就给我钱。(与现在事实相反)

　　I would rather you had attended the meeting yesterday. 我希望你昨天参加会议了。(与过去事实相反)

　　5．虚拟语气用于以as if (as though) 引导的表语从句或状语从句中。

　　如果从句表示与现在事实相反，谓语动词用一般过去时；表示与过去事实相反，谓语动词用“had ＋过去分词”；表示与将来事实相反，谓语动词用“would (might, could) ＋动词原形”。

　　The coach always treats the players as if they were his own children.教练对待队员就像是对自己的孩子。

　　She was suffering from a bad cold. Her head felt as if it would burst。她正患重感冒，头疼的感觉就像要炸开一样。

　　但as if (as though) 后的从句也常用陈述语气，这是因为从句中的情况往往是可能发生的或可能被设想为真实的。

　　It looks as if it is going to rain. 似乎要下雨。

　　6．虚拟语气用于if only引导的感叹句中。

　　If only I knew his name！我要是知道他的名字就好了。

　　If only I had known the answer when my teacher questioned me.老师提问时，我要是知道答案就好了。

　　7．“It's necessary / strange / natural / important ＋ that...”在主语从句中的动词要用虚拟，即(should)＋动词原形，表示惊奇、不相信、惋惜、理应如此等。

　　It is important that we (should) have a good knowledge of computer in modern times.在现代社会，有电脑常识是非常重要的。

　　It is necessary that these useful expressions (should) be learnt by heart.我们记住这些有用的表达方式是很有必要的。

　　It is suggested that she should finish her task this afternoon.有人建议她下午就应完成任务。

　　注意：这种从句表示的是事实，如果不表示惊奇，that从句也可用陈述语气。

　　8．表语从句和同位语从句中的虚拟语气。

　　在 suggestion, proposal, idea, plan, order, advice 等名词后面的表语从句、同位语从句中要用虚拟语气，即 (should) ＋动词原形。

　　My suggestion is that the project (should) be completed by the end of the year.我建议工程应该在年底前竣工。

　　We all agreed to his suggestion that we (should) go to Beijing for the National Day military parade.他提出去北京看国庆阅兵的建议，我们都非常赞成。

　　9．虚拟语气用于定语从句

　　这种从句常用在“It is (high) time (that) ...”句型中，定语从句的谓语动词用过去式，或“should ＋ 动词原形(should不能省略，be用were)”来表示，意为“(现在)该……”。

　　It's high time that you should stop smoking.你该戒烟了。

　　10．虚拟语气用于其他几种结构

　　在某些虚拟语气结构中没有if条件句，虚拟条件是用其他形式表示出来，这种现象在语法上称为“含蓄条件句”。含蓄条件具体分为以下几种情况：

　　1)通过动词不定式短语表示条件

　　You would be a fool to refuse his offer. ＝ If you should refuse his offer, you would be a fool. 要是你拒绝他的建议，就太傻了。

　　2)通过介词短语表达条件

　　But for your help, we couldn't have succeeded. ＝ If it had not been for your help, we wouldn't have succeeded. 要不是你的帮忙，我们就不会成功了。

　　3)通过连词otherwise, or, but, that, though, once等表达条件

　　She wasn't feeling very well. Otherwise she would have attended the meeting.她本可以参加会议，但是她当时感觉不舒服。

　　4)通过“Were it not for...”或“Had it not been for...”等句式表达条件

　　Were it not for / If it were not for the leadership of the Party, we could not live a happy life.要不是党的领导，我们不可能过幸福生活。(与现在事实相反)

　　Had it not been for the kind guide, I might have got lost in the mountains.要不是这位好心的向导，我可能就在山中迷路了。 (与过去事实相反)

　　5)通过分词短语表达条件

　　Given more information, they could have done the job better.倘若给予更多的信息，他们本来可以把工作做得更好。(＝ If they had been given more information...)

　　高考对情态动词的考查命题热点主要集中在以下几个方面：

　　1．注重在语言环境中根据说话人的语气来使用情态动词。

　　2．情态动词表示推测或判断的用法考查。

　　3．设置场景考查学生熟练使用表示责备等的情态动词加完成时的用法等。

　　4．虚拟语气是历年高考的选考考点，考点常集中在含蓄条件句以及宾语从句中的虚拟语气上。所设选项常通过谓语动词的特殊形式来表示， 而且都是结合具体语境来考查对考点的运用能力。今后高考对虚拟语气的命题重点仍会是在特定语境中考查虚拟语气中的含蓄虚拟条件句、宾语从句中的谓语动词等。2011全国卷,32】They

　　have arrived at lunchtime but their flight was delayed.

　　A.will

　　B.can

　　C.must

　　D.should

　　D

　　【考点】考查虚拟语气的用法。

　　【解析】句意为“他们本该午饭时到达，但他们的航班推迟了。”will have done将来可以完成；can have done可能做过……吗？表示对过去行为的怀疑，用于疑问句；must have done一定做过某事，表示对过去事情的肯定推测；should have done本来应该做某事，而实际没做。but their flight was delayed这样的结果，说明他们本来该到达却没有到达，因此选D。

　　2011全国卷II,8】If you

　　smoke, please go outside.

　　A. can

　　B. should

　　C. must

　　D. may

　　C

　　【考点】考查情态动词的用法。

　　【解析】句意为“如果你非得要抽烟，请到外面去抽。”must (表示主张)一定要，坚持要。根据后一句please go outside的要求，选C。

　　2011北京卷,24】——I don’t really like James. Why did you invite him?

　　Don’t worry. He

　　come. He said he wasn’t certain what his plans were.

　　A. must not

　　B. need not

　　C. would not

　　D. might not

　　【答案】D

　　【考点】考查情态动词的用法。

　　【解析】句意为“——我真不喜欢James。你为何请了他？——别担心。他可能来不了。他说他的计划还没安排好。”题干中的he wasn’t certain说明他可能不来，可能来，因此使用不完全否定might not。选D。

　　2011北京卷,28】——Where are the children? The dinner’s going to be completely ruined.

　　I wish they

　　always late.

　　A. weren’t

　　B. hadn’t been

　　C. wouldn’t be

　　D. wouldn’t have been

　　【答案】A

　　【考点】考查虚拟语气的用法。

　　【解析】句意为“——孩子们哪儿去了？这顿饭快要吃不起来了。——我但愿他们不要老是迟到。”wish引出虚拟语气，题干中出现always，从句虚拟使用一般过去时。选A。

　　2011北京卷,30】Maybe if I

　　science, and not literature then, I would be able to give you more help.