2021版高三英语人教版一轮复习讲义：语法情态动词和虚拟语气语法精练

情态动词和虚拟语气一、情态动词考点一　情态动词的基本用法1.can和could的用法(1)表示“能力”。The man can∕could speak two foreign languages.那个人能说两门外语。(2)表示推测,一般用于疑问句和否定句。—Can the news be true?——这个消息可能是真实的吗?—It can’t be true.——它不可能是真实的。(3)表示可能性。用于肯定句,常译为“往往会,常常会,有时候可能会”。The weather in Ningbo can be very cold in winter.宁波的冬天会很冷。(4)表示请示、允许。口语中常用could代替can。could用以委婉地提出请求等,但回答时必须用can。Can I have a rest?我能休息一下吗?Could you please help fill this form?你能帮助我填下这个表格吗?(5)cannot...too∕enough表示“无论……也不过分”“越……越好”。　You can’t be too careful while driving.开车时越小心越好。You cannot remember enough English words.你记的英语单词越多越好。2.may和might的用法(1)表示许可。might比may的语气更委婉。You may use my bike.你可以用我的自行车。(2)表示推测,意为“可能”。may not表示一种不太确定的语气,意为“可能不”。Some people who don’t like to talk much are not necessarily shy; they may just be quiet people.言语不多的人未必就是害羞;他们或许就是安静的人。(3)may表示请求时,其否定式常用mustn’t表示“禁止”。　—May I use your car?——我可以用一下你的车吗?—No,you mustn’t.——不行。(委婉拒绝可用:Sorry,but I’m using it now.或You’d better not.)(4)表示祝愿,常用结构为“May+主语+动词原形!”May you be happy every day!愿你快乐每一天!3.must(1)表示义务,意为“必须”(主观意志)。We must do everything step by step.我们一切都必须循序渐进地做。 回答以must开头的问句时,若是否定回答,需要用 needn’t 或 don’t have to。— Must we hand in our exercises today?——我们今天必须交练习吗?—Yes,you must.∕No,you needn’t∕you don’t have to.——是的,必须交。∕不,不必今天交。(2)表示推测,意为“一定,必定”,表达十分肯定的语气,只能用于肯定句中。He must be ill.He looks so pale.他准是病了。他脸色苍白。(3)表示“非得,偏要”。Must you play the piano in such late a time?你非要在这么晚的时间弹钢琴吗?4.shall和should的用法(1)shall①用于第二、三人称的陈述句中,表示命令、许诺、警告、强制、威胁等,此外,颁布法律、法规时也用shall。You shall have a new bike for your birthday.你会得到一辆新自行车作为生日礼物。The new law shall come into effect next month.新法将于下个月生效。②用于第一、三人称的疑问句中,表示说话人征求对方的意见或向对方请示。Shall the man standing outside have a try?让站在外边的那个人试试?(2)should①表示义务,常译为“应该”,用于各种人称。Parents should take good care of their babies.父母应该照顾好他们的孩子。②表示惊讶、意外等,常译为“竟然,居然”。I am surprised that you should speak ill of me.我很惊讶,你竟然说我坏话。5.will和would的用法(1)表示意愿,用于各种人称的陈述句中。would常指过去的意愿。If you want to read the book,I’ll give it to you.如果你想读这本书,我可以给你。(2)表示请求,用于疑问句。would语气较委婉。Will you close the window?请你关上窗户好吗?(3)表示某种倾向或习惯性动作,常译为“总是,习惯于”。would可表示过去反复发生的动作或某种倾向,后面接表示动作的动词,不能接表示状态的词。Every morning he will have a walk along the river.每天早晨,他总是沿着小河散步。 used to表示过去的习惯动作或状态,强调现在已不存在。The old woman would sit in front of the door,watching the people go by.那个老太太总是坐在门前,看着人们走过。It used to be a factory,but now it is a big supermarket.它过去曾经是一个工厂,但是,现在它已经是一个很大的超市了。6.need和dare的用法need和dare既可用作情态动词,也可用作实义动词。用作情态动词时,主要用于否定句和疑问句。—Need I come?——我需要来吗?—Yes,you must.——是的,你必须来。You needn’t telephone him now.你现在不必打电话给他。She dare not go out alone at night.她晚上不敢一个人出去。考点二　“情态动词+have done”的用法1.对过去发生的事情或状态进行推测must have done(过去)一定……;语气比较肯定;用于肯定句may(might) have done(过去)可能……;语气不确定;用于肯定句和否定句can(could) have done(过去)可能……,用于否定句和疑问句,表示怀疑或不确定Since nobody gave him any help,he must have done the research on his own.既然没有人帮助他,他一定是独自做的研究。Could he have left the work unfinished?他会丢下工作不干了?2.表示“与过去事实相反”could have done过去本可以做某事但实际上没做needn’t have done过去本不必做某事但实际上做了ought to∕shouldhave done过去本应该做某事但实际上没做oughtn’t to∕shouldn’t have done过去本不应该做某事但实际上做了would have done过去本来想做某事而没做would not have done过去本不愿意做某事而做了I could have done better in the last exam.上次考试我本应该考得更好。You needn’t have watered the flowers because it would rain soon.你本不必浇花的,因为很快会下雨的。(已经浇了)I would have helped you but I was busy at that time.我本来想帮你可是当时很忙。(没有帮)二、虚拟语气1.非真实条件句中虚拟语气的用法说明if条件句谓语主句谓语与现在事实相反动词的过去式(be的过去式用 were)would∕should∕could∕might+动词原形与过去事实相反had+过去分词would∕should∕could∕might+have+过去分词与将来事实相反动词的过去式(be的过去式通常用were),should do,were to+动词原形would∕should∕could∕might+动词原形If I were you,I would go with him.如果我是你,我就和他一起去。If you had studied harder last term,you could have passed the exam.如果上学期你学习更努力的话,你考试就会及格了。If it snowed tomorrow,we would take photos.如果明天下雪,我们就照相。 条件句中有were,had或should时,如果省略if,则需把were,had或should放在主语前,构成倒装结构。如:If I were in your position,I would do the same.→Were I in your position,I would do the same.假如我处在你的位置,我也会这样干的。If you had come earlier,you would have caught the bus.→Had you come earlier,you would have caught the bus.如果你来得早些,你就会赶上公共汽车了。If it should rain tomorrow,we would not go climbing.→Should it rain tomorrow,we would not go climbing.如果明天下雨的话,我们就不去爬山了。2.错综时间虚拟条件句当从句谓语动词与主句谓语动词所发生的时间不一致时,它们的形式要根据各自所表示的时间作出相应的调整。If you had worked hard,you would pass the exam this time.(从句指过去,主句指现在)如果你之前努力学习的话,你就会通过这次考试了。3.含蓄虚拟语气有时,假设的情况并不用条件从句表达,而是暗含在上下文中,由otherwise,but,or,without,but for 等组成的词组来表达。But for your help,we couldn’t have succeeded.(介词短语)　要不是你的帮助,我们是不会成功的。Without electricity,life would be quite different today.(介词)如果没有电,今天的生活就会完全不同。I was ill that day.Otherwise,I would have taken part in the sports meeting.(副词)我那天病了。否则,我就参加运动会了。He telephoned to inform me of your birthday,or I would have known nothing about it.(连词)他打电话通知了我你的生日,否则,我对此一无所知。4.某些从句中虚拟语气的用法(1)用于表示建议、愿望、命令等动词后的宾语从句中。常见的动词有:demand,order,require,insist,suggest,advise,request,urge,command,recommend等。宾语从句中的虚拟语气结构为“should+动词原形”,should 可以省略。[记忆口诀]一主张:insist二命令:order,command三建议:suggest,advise,recommend四要求:request,require,ask,demand外加一个敦促:urgeThe school recommends parents not permit their children to swim in rivers or lakes during summer holidays.学校建议父母们在暑假期间不要让自己的小孩在河里或湖里游泳。 当suggest作“暗示,表明”,insist作“坚持认为,坚持说”讲时,从句要用陈述语气。The expression on his face suggested that he was very angry.他脸上的表情表明他很生气。He insisted (that) he heard someone in the next room.他坚持说他听到隔壁屋里有人。(2)wish后跟宾语从句时用虚拟语气。对现在情况的假设:wish+主语+动词过去式(be动词用were)对过去情况的假设:wish+主语+had+过去分词对将来情况的假设:wish+主语+would∕could∕might+动词原形I wish (that) I were a bird and could fly freely in the sky.我希望我是只小鸟,能在天空自由飞翔。How I wish I had listened to my parents’ advice!我多么希望我听了父母的建议!I wish I could fly to the moon some day.如果有一天我能飞到月球上就好了。(3)在“It is necessary∕important∕strange∕natural∕essential+that从句”中,谓语动词常用“ should+动词原形”,should 可以省略。It is important that every member (should) know these rules.重要的是每个成员都应该知道这些规则。It is necessary that students (should) respect teachers.学生应该尊重老师,这是必须的。(4)would rather后跟从句时用虚拟语气,表示愿望,意为“宁愿;但愿”。George is going to talk about the geography of his country,but I’d rather he focused more on its culture.乔治打算谈论他国家的地理,而我宁愿他更多地关注他国家的文化。(5)在“It is (about∕high) time+that 从句”中,谓语动词常用过去式或“should+动词原形(其中should不能省略)”。此句型意为“(现在)该……”,用来表示建议。It is time that you went to school.你该去上学了。It is (high) time that we should start out.我们(早)该出发了。(6)if only引导的感叹句中,用虚拟语气表示愿望。Look at the trouble we’re in.If only we had taken our teacher’s advice!瞧瞧我们所处的困境,要是我们采纳了老师的建议就好了!(7)as if,as though 引导的表语从句和方式状语从句中常用虚拟语气,与现在事实相反用一般过去时(be动词用were);与过去事实相反用过去完成时;与将来事实相反,用would∕could∕might+动词原形。It seems as though it were spring already.看起来好像已经是春天了。(事实上不是)The girl is giving us a vivid description of the moon.It seems as if she had been to the moon many times.这个女孩对月球的描述非常逼真,就好像她去过月球很多次似的。(事实上并没去过)He opens his mouth as if he would say something.他张开嘴巴,好像要说什么。1.The workers were not better organized,otherwise they 　　　　 (accomplish) the task in half the time.(2019天津) 2.What a pity!You missed the sightseeing,or we 　　　　(have) a good time together.(2019江苏) 3.If he 　　　　 (react)quickly,there could have been a terrible accident.(2017年11月浙江) 4.Samuel,the tallest boy in our class,　　　　 easily reach the books on the top shelf.(2017北京) 5.My room is a mess,but I 　　　　 clean it before I go out tonight.I can do it in the morning.(2017天津) 答案及剖析:1.would have accomplished　考查虚拟语气。句意:工人们没有被更好地组织,否则他们会用一半的时间完成任务。此处表示与过去事实相反的假设,用would have done sth.表示“本来能够做某事”。2.would have had　考查虚拟语气。句意:真遗憾!你错过了观光,否则我们在一起会玩得很开心。根据What a pity!You missed...以及or(否则)可知,此处是与过去事实相反的虚拟语气,故用would have done结构。3.hadn’t reacted　考查虚拟语气,此处的语境是“如果不是他快速采取行动,那么将会有一场严重的交通事故”。讲述的是过去发生的事情,在条件从句中应该用hadn’t done。4.can　本题考查情态动词。本句的句意:塞缪尔是我们班里最高的男孩,他可以轻松地够到书架顶层的书。根据语义可知应用情态动词can“可以,能够”表示能力。5.needn’t　本题考查情态动词。句意:我的房间很乱,但是在今晚外出之前我不需要打扫它,我可以在(明天)早晨打扫。根据语境可知,我不需要打扫或没必要打扫房间,用needn’t符合题意。