高三英语一轮复习情态动词和虚拟语气专题讲义.docx

情态动词和虚拟语气【知识梳理1】情态动词考点一：can与could1. 表示能力, 但could主要指过去的能力。表示“过去有能力做成某事”时通常用was/were able to。The little boy can speak two foreign languages. 这个小男孩会讲两种外语。2. 表示可能(理论上或是逻辑判断上, 并不涉及此事真的发生), 常译为“往往会, 有时候可能会”, 常用于肯定句中。Although you can find bargains in London, its not generally a cheap place to shop. 虽然你有可能在伦敦买到便宜的东西, 但通常而言这不是个买便宜东西的地方。3. 表示请求和允许。在问句中could语气比can要委婉。Can I have a word with you?It wont take long. 我能和你说会话吗?不会占用你很长时间。4. 表示惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。How can you be so careless?你怎么能这么粗心?5. 表示推测, 常用于否定句和疑问句中, 语气较强。He cant be in the classroom, the light is not on. 他不可能在教室里，灯没亮。Why are your eyes so red? You cant have slept well last night. 你的眼睛为什么红红的?你昨天晚上一定没有睡好。6. cannot/can never. . . too/enough. . . 表示“再也不为过”。You can never be too careful when driving a car. 开车的时候再小心都不为过。7. cannot but do sth. /cannot help but do sth. /cannot choose but do sth. 表示“不得不/只好做某事”。You cannot choose but go with me. 你只能跟我走。考点二：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、决心等；此外, 颁布法律、规定时也用shall。You shall do as your father says. 你要按照你父亲说的那样做。One of our rules is that every student shall wear school uniform while at school. 我们规定中的其中一项是:每位学生在校期间都要穿校服。Each party shall respect the articles of this contract. 任何一方都要尊重合同的条款。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指示。Shall the man standing outside have a try?站在门外的那个人可以试试吗?考点三：must1. 表示主观上的“必须, 应该”, 其否定形式mustnt表示禁止。对比:have to表示客观上的“不得不”, 可用于各种时态。以must开头的问句, 其否定回答用neednt或dont have to。Must I clean the dining room at once?No, you neednt/No, you dont have to. 我必须马上打扫餐厅吗?不, 你不必。2. 表示“非要, 偏要”做某事, 表达出说话者的一种不满情绪。Can I smoke here?No. Go to the smoking section, if you must. 我能在这里抽烟吗?不能, 如果你非要抽烟的话, 就去吸烟区吧。Why must you be talking so loudly when others are sleeping?别人都在睡觉, 为什么你偏要这么大声说话?3. 表示对具体事情的推测, 意为 “一定, 肯定”, 语气较强, 只用于肯定句中。Since nobody gave him any help, he must have done the research on his own. 既然没有人给他任何帮助, 那他一定是独自完成的这项研究。考点四：should和ought to1. 表示义务, 常译为“应该”, 用于各种人称。ought to的语气比should强烈。Parents should/ought to take good care of their babies. 父母应该照看好他们的孩子。2. should表示推测, 译为“可能, (按道理)应该”, 多指对未来合乎理想的情况或结果的一种期盼。Its nearly 8 oclock. He should be here at the moment. 快八点钟了。此刻他应该在这儿了。3. should表示惊讶、意外等, 常译为“竟然, 居然”。You should wear slippers in the classroom. 你竟然在教室里穿着拖鞋。4. 用在if条件句中, should表示可能性很小的一种虚拟语气。If I should see him, I would tell him the news. 如果我见到他, 我就告诉他这个消息。考点五：will和would1. 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 will read the book, Ill give it to you. 如果你愿意读这本书, 我就给你。2. 表示请求、建议, 常用于第二人称, 用在疑问句中。would语气较委婉。Will you please 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, 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。对比:used to表示过去的习惯动作或状态, 强调现在已不存在。The door wouldnt open, no matter how hard she pushed. 无论她怎么用力推, 这扇门就是打不开。考点六：may与might1. 表示请求、允许、许可, might比may语气委婉。You may use my bike. 你可以用我的自行车。2. 表示推测, 常用于陈述句中, 语气比较弱, 把握性不大。might语气比may还要弱。Life is unpredictable; even the poorest might/may become the richest. 生活是不可预测的, 甚至是最穷的人也可能会变成最富的。3. may/might as well+动词原形, 意为“最好, 倒不如”。You may/might as well do it at once. 你最好立刻开始做。4. may well+动词原形, 意为“完全能, 很可能”。He may well be late for class. 他上课很可能迟到。5. may用于祈使句中, 表示祝愿。May you return in safety. 祝你安全归来。考点七：need和dare1. 两者都可以作为情态动词和实义动词。当作情态动词时, 后面要接动词原形, 通常用于否定句、疑问句和条件句中。用作实义动词时, 其变化和一般的动词相同, 有人称和数的变化, 构成否定句和疑问句时要借助于助动词do, does, did。dare用作实义动词, 用于否定句和疑问句时, 常省略后面的to。Ive prepared all kinds of food for the picnic. Do you mean we neednt bring anything with us?我已经为野餐准备了各种各样的食物。你的意思是我们不必带任何东西了?The little girl didnt dare(to) go out at night alone. 小女孩晚上不敢独自外出。2. need用作实义动词时, 若主语为动作的承受者时用谓语动词的主动形式表示被动意义或用不定式的被动形式。The house needs repairing. =The house needs to be repaired. 这个房子需要维修。3. I dare say为习惯说法, 意为“我想, 大概”。I dare say she dare not speak to her father in this manner. 我想她不敢用这种方式跟他父亲说话。考点八：情态动词表推测1. can, may, must皆可用来表示推测。(1)在肯定句中都可以用来表示可能性。在含义上must语气最肯定, may表示不太肯定的可能性, 而can表示理论上的可能性。(2)在否定句中只能用cannot/cant和may not。cant(不可能)语气比may not(可能不、也许不)更强。(3)在疑问句中只能用can, 不能用may和must。Accidents can happen on such snowy days. Look, there is some blood on the road; an accident must have happened just now. But it cant have been Mike, for I saw him in the school. 这样的下雪天可能会发生事故。看, 公路上有血;刚才一定发生事故了。但肯定不是迈克, 因为我看见他在学校里。2. should 与ought to 可以表示对未来情况的一种期盼, 常译为“按理应当”。He should/ought to be here on timehe started early. 他应该能按时到达这儿他很早就出发了。考点九：情态动词+have done1. could have done的疑问或否定形式表示对过去发生的行为表示怀疑或不肯定, 其中couldnt have done 多用于语气强烈的否定, 意为“过去不可能做过”。could have done在肯定句中表示“本来能做但却没做”。The accident could have been avoided; the driver couldnt have slowed down. 这事故本来是可以避免的;司机肯定没减速。2. may/might have done 表示对过去行为的推测, 意为“可能做过”。might 所表示的可能性比较弱, 此外might have done 还可表示“本可能做而实际上未做”, 含有轻微的责备语气。You might have given him more help, though you were busy with your work. 你本来可以给他更多的帮助, 尽管你工作很忙。3. must have done 表示对过去行为的推测, 意为“一定, 想必做过”, 语气十分肯定。It must have rained last night, as the ground is wet. 昨晚一定下雨了, 因为地面是湿的。4. should/ought to have done 用于肯定句时, 表示“本该做某事而实际上未做”;用于否定句时, 则表示“不该做某事反而做了”。Sorry, Mum! I failed the job interview again. Oh, its too bad. You should have made full preparations. 对不起, 妈妈, 我这次工作面试又失败了。太糟糕了。你本来应该进行充分准备的。5. neednt have done表示“本来不必做某事而实际上却做了”。I actually neednt have bought so much foodonly three people came. 我实际上不必买这么多食物只有三个人来了。6. had better have done 用于事后的建议, 含轻微责备的口吻, 意为“当时最好做了某事”。I had better have started earlier. 我要是早点起程就好了。7. would rather have done sth. 表示“宁愿当时做某事”, 其否定形式would rather not have done sth. 表达相反的含义, 两者都含有“后悔”之意。I would rather have taken his advice. 我宁愿当时接受了他的建议。8. would like/love to have done sth. 表示“过去愿意做某事但未做成”。I would love to have gone to the party last night, but I had to work extra hours to finish my report. 我昨天晚上本想去参加聚会来, 但我不得不加班写完报告。【知识梳理2】虚拟语气考点一：虚拟语气用于条件句中1. 表示与现在事实相反:条件状语从句中谓语动词用过去式(be的过去式用were);主句中谓语用would/should/could/might+动词原形。We would be back in the hotel now if you didnt lose the map. 如果你没丢失地图的话, 我们现在就回到旅馆了。2. 表示与过去事实相反:条件状语从句中谓语用had+过去分词;主句中谓语用would/should/could/might+have+过去分词。If Mr Dewey had been present, he would have offered any possible assistance to the people there. 如果杜威先生在场的话, 他会给那里的人们尽可能地提供帮助。3. 表示与将来的事实相反:条件状语从句中谓语用过去式或should+动词原形或were to+动词原形;主句中谓语用would/should/could/might+动词原形。Grace doesnt want to move to New York because she thinks if she were to live/should live/lived there, she wouldnt be able to see her parents very often. 格雷丝不想搬到纽约去, 因为她认为如果她住在那儿的话, 就不能经常见到她的父母了。4. 虚拟条件句有时候假设的情况不以if引导的条件句形式表现出来, 而是通过一个介词短语、连词或其他形式表示。常用的词或短语有:without, with, but for(要是没有), otherwise, or, but等。Without his wartime experiences, Hemingway wouldnt have written his famous novel A Farewell to Arms. 如果没有战时的经历, 海明威就不会写出他的著名小说永别了, 武器。But for your advice, I could not have done it so successfully. 要是没有你的建议, 我就不会这么成功。5. 错综时间条件句中的虚拟语气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, 称为“错综时间条件句”, 动词的形式要根据主从句所表示的时间作出相应的调整。If we had booked a table earlier, we wouldnt be standing here in a queue. 如果我们早点儿预订一张桌子, 我们就不用站在这儿排队了。(从句说的是过去的情况, 主句说的是现在的情况)6. 省略if的虚拟语气如果if从句中含有were/should/had时, 则可以省略if, 把这三个词置于句首, 采用倒装语序。If I were you, I would go to the party. Were I you, I would go to the party. 考点二：wish宾语从句中的虚拟语气在wish后的宾语从句中, 表示与现在或过去的事实相反, 或对将来的主观愿望, 从句中通常用虚拟语气。从句中谓语的构成形式为:1. 表示对现在情况的虚拟, 从句中谓语动词用过去式(be动词用were)。Do you like the school?Yeah. I only wish the classes were a little smaller. 你喜欢这个学校吗?是的。我只希望班级小一些。2. 表示对过去情况的虚拟, 从句中谓语动词常用had+过去分词。I wish I had been at my sisters wedding last Tuesday, but I was on a business trip in New York then. 我多么希望自己上个星期二能参加姐姐的婚礼呀, 可是我当时正在纽约出差。3. 表示对将来的主观愿望, 从句中谓语动词常用would/could/might+动词原形。I wish it would be fine tomorrow. 我希望明天有个好天气。考点三：谓语动词必须用（should）+动词原形的情况1. 表示“建议, 要求, 命令”的动词:一坚持(insist), 二命令(order, command), 三建议(suggest, recommend, advise), 四要求(demand, require, request, ask)后面的宾语从句或由it做形式主语的主语从句中的谓语要用“(should+) 动词原形”。这些动词相应的名词后的表语从句和同位语从句中的谓语也要用“(should+) 动词原形”。The teacher ordered that the homework (should) be handed in on time. 老师要求我们按时上交作业。注意suggest当“表明, 暗示”讲时, 不用虚拟语气;insist 当“坚持认为”讲时, 不用虚拟语气。The smile on his face suggested he was happy. 他脸上的笑容表明他很开心。The boy insisted he hadnt stolen the money. 那个男孩坚持说他没有偷钱。2. 在It is important/strange/natural/necessary/a pity/a shame等+that从句, 表示情绪、观点等, 主语从句中的谓语用“(should+) 动词原形”。It is a pity that he (should) refuse to accept the offer. 遗憾的是他拒绝接受那个提议。考点四：虚拟语气的其他用法1. 在as if/as though引导的状语从句中, 若从句与事实相反, 则要用虚拟语气。具体情况如下:当从句的动作与主句的动作同时发生时, 从句谓语动词用过去式。当从句的动作发生于主句的动作之前时, 从句谓语动词用过去完成式。2. 在It is (high/ about )time that. . . 句型中也用虚拟语气, 从句谓语动词常用过去式或者should + 动词原型（其中should不可省略）, 表示“是时候做了”, 含“建议”的意味。Jack is a great talker. Its high time that he did something instead of just talking. 杰克是个空谈家。到了他做点事而不是夸夸其谈的时候了。3. would rather后接动词原形, 但接从句时要用虚拟语气(宁愿, 但愿)。具体情况如下:当从句表示与现在或将来事实相反时, 从句谓语动词用过去式。当从句表示与过去事实相反时, 谓语动词用过去完成式。4. if only “要是就好了”。表示与现在或将来事实相反的愿望时, 句子谓语动词用过去式;表示与过去事实相反的愿望时, 句子谓语动词用过去完成式。If only I had passed the driving test last week!要是我通过了上周的驾驶考试就好了!【例题精讲】例1：_not for the support of the teachers, the student could not overcome her difficulty. A. It were B. Were it C. It was D. Was it答案B句意:没有老师们的支持, 这个学生不可能克服她的困难。本题考查虚拟语气。根据题干中的the student could not overcome可知, 语境是对现在事实的虚拟, be动词在虚拟语气中通常用were。当虚拟语气中if引导的条件句省略了if时, 从句部分应使用倒装结构, 故选择B项。例2：If it _ for his invitation the other day, I should not be here now. A. had not been B. should not be C. were not to beD. should not have been答案A句意:如果不是因为那天他的邀请, 我现在是不会在这里的。本题考查虚拟语气。根据语境可知, 本题用了虚拟语气, 又根据主句中的now和从句中的the other day可知本句是一个错综时间条件句, 主句和现在的事实相反, 从句和过去的事实相反, 故从句用过去完成时态。例3：Samuel, the tallest boy in our class, _easily reach the books on the top shelf. A. must B. should C. can D. need答案C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。本题考查情态动词。根据语义可知应用情态动词can“可以, 能够”表示能力。must必须, should应该, need需要, 均不符合句意。例4：My room is a mess, but I_clean it before I go out tonight. I can do it in the morning. A. darent B. shouldnt C. neednt D. mustnt答案C句意:我的房间很乱, 但是在今晚外出之前我不需要打扫它, 我可以早晨打扫。本题考查情态动词。根据语境可知, 我不需要打扫或没必要打扫房间, 用neednt符合题意。Darent不敢, shouldnt不应该, mustnt表禁止, 均不符合题意。例5：George_too far. His coffee is still warm. A. must have gone B. might have goneC. cant have gone D. neednt have gone答案C句意:乔治不可能走太远。他的咖啡还是热的。本题考查情态动词。Cant have done sth. 不可能做过某事;must have done sth. 一定做过某事;might have done sth. 可能做过某事;neednt have done sth. 本不必做某事。根据句意选C项。例6. If the new safety system _ to use, the accident would never have happened. A. had been put B. were put C. should be put D. would be put【答案】A【考点】虚拟语气【解析】考查虚拟语气。句意：如果这个新的安全系统被投入使用过的话，这个事故就不会发生了。主句是对过去的虚拟，所以从句用had done的形式，system和put to use是动宾关系，故选A。例7. Do you have Bettys phone number?来源:ZYes. Otherwise, I _ able to reach her yesterday. 来源:A. hadnt been B. wouldnt have been C. werent D. wouldnt be【答案】B【考点】虚拟语气【解析】句意：你有贝蒂的电话号码吗？有。否则我昨天就联系不到她了。此处otherwise(否则)相当于一个条件状语从句，由yesterday可知本句对过去进行虚拟，由此可以判断出主句用wouldnt have done，故选B。