用过去式表示的虚拟语气.doc

用过去式表示的虚拟语气在虚拟条件句中的运用1. 与现在事实相反：条件句的谓语动词用一般过去式(be一般用were) ，主句谓语用would /should /could /might +动词原形。如：If I were you, I would never do that. 如果我是你,我决不做那件事。If it werent for (=But for) your help, I would still be homeless. 若不是你帮忙，我现在还是无家可归。If I had more money, I would buy a car. 我要是有再多一点钱，我就买汽车了。注：在口语中，在第一、三人称后，也有人用was。如：If I was(were) rich, I would buy a car. 我要是有钱，我就买汽车了。2. 与将来事实相反：条件句中的谓语可用一般过去式、或者“were to /should动词原形”，主句谓语用would /should /could /might +动词原形。如：If it rained/should rain/were to rain tomorrow, I would not go there. 要是明天下雨，我就不去那里。3. 与过去事实相反：条件句的谓语动词用过去完成式，主句谓语用would /should /could /might + have +过去分词。如： If he had taken my advice, he might not have made such a bad mistake. 要是他当初听从我的劝告就不会犯这么严重的错误了。If it hadnt been for Margaret, I might not have understood. 要不是有玛格丽特，我可能还不明白。注：若虚拟条件句中有were, should, had时，可省略if，将were, should, had移至主语前。如：Were I you, I would never do that. Should it rain tomorrow, I wouldnt go there. Had it not been for Margaret, I might not have understood. 在错综时间虚拟条件句中的运用虚拟条件句与主句谓动词发生的时间有时不一致，要注意主从句谓语动词的形式。如：If youd listened to me, you wouldnt be in such trouble now. 如果你当初听了我的话，你现在也不会有这样的麻烦了。在含蓄虚拟条件句中的运用有时只有主句，不出现虚拟条件句，而是用without, with, but for(要不是) 等介词短语，或者用but, or, otherwise等副词或连词，或者用不定式或分词短语等来表示虚拟条件。如：But for (=if it had not been for ) your help, I wouldnt have been successful. 要是没有你的帮助，我就不会成功。I was so busy then, otherwise, I would have helped him. 我当时很忙，要不然，我会帮助他的。We couldnt have finished it without Mary. 如果没有玛丽，我们是不能按时完成这个工作的。To hear him talk (=If you could hear him talk) , youd think he was Prime Minister. 听他讲话你会以为他是首相。Given more time, I could have done it better. 要是多给一点时间，我会做得更好。 在wish, if only, as if, would rather等后的从句中这些从句的谓语动词的形式是：若与现在或将来事实相反，用一般过去式(动词be一律用were) ；若与过去事实相反，用过去完成式。如()：I wish it were spring here all the year round. 但愿这里四季如春。I wish I hadnt wasted so much time. 但愿当初不该浪费这么多时间就好了。If only she would go with me! 她要是愿意和我一道去就好了!If only I had listened to my parents! 我要是听了我父母的话就好了。Li Ming speaks English as if he were an American. 李明说英语好像是美国人。I would rather he came tomorrow. 我宁愿他明天来。Id rather he hadnt told me about it. 我宁愿他没告诉我这事。注：as if/as though引导的从句若是事实，就不必用虚拟语气。如：It looks as if it is going to rain. 看起来要下雨的样子。 as if/as though引导的从句中He speaks English as though he were an American. 他说英语跟美国人差不多。在Its time that的that从句的谓语动词It is time that we got ready for the final examination. 该是我们为期末考试做准备的时候了。情态动词must用法详解湖南 龙 楠(1) 表示“必须”此时可用于肯定句、否定句或疑问句，用于否定句时，mustnt的意思是“一定不要”“不能”，而不表示“不必”。如：Water must be pure if it is to be drunk. 水如供饮用必须净化。Must I finish the work tonight? 我必须今晚完成这项工作吗? Adverbs mustnt be put between the verb and the object. 副词不能放在动词和宾语之间。must主要表示现在或将来，但在间接引语中也可表过去(=had to)。如：She asked her boss if she must (had to) work overtime. 她请示上司她是否要加班。对于must开头的一般疑问句，若作否定回答，可以用neednt，不用 mustnt。如：“Must I clean all the rooms?” “No, you neednt.” “这些房间我都得清扫吗?”“不必。”(2) 表示推测意为“准是”“一定是”，通常只用于肯定句。若用于否定句或疑问句，则用 can 代之。如：That cant be the only way. There must be other ways of solving the problem. 那不是解决问题的唯一办法，肯定有另外的办法。Janes light is on. She must be at home. She cant be out. 简的房间里开着灯。她一定在家，不会出去的。若要谈论过去的情况，必须用“must+have+过去分词”。如：You must have mistaken my intention. 你一定是误会了我的意图。She must have been very young when she got married. 她结婚时一定很年轻。He must have come this way; here are his footprints. 他一定是走这条路来的，这里还有他的脚印呢。(3) 表示“偏偏”有时must可表示某事发生得不早不迟，就在某个当紧的时候，多指某些不受欢迎的事情的发生。如：The car must break down just we were starting our holidays. 我们刚刚开始休假，汽车偏偏坏了。Must you worry her with questions, just when she is busy cooking dinner? 她正忙着做饭你干吗偏偏问她问题? Just when I was busy, the neighbor must come and chatter. 正当我忙碌的时候，邻居偏偏过来聊天。有时还可指主观上的偏执或固执，常可译为“偏”“偏要”。如：After I gave her my advice，she must go and do the opposite. 在我给她出主意之后她偏要反着干。Must you make so much noise? 你就非得弄出这么大的声音吗？(4) must 与 have to 的区别两者都表示“必须”，但must 侧重于说话者的主观看法，认为有必要或有义务去做某事；have to 则重于客观需要，含有“不得不”“被迫”之意。如：Everyone must keep the law. 人人都要守法。The last train has gone. Well have to walk home. 最后一班车已经开了，我们得走回家了。从时态方面看，must 只有现在时一种形式(在宾语从句中可以表示过去)，而 have to 则有多种时态形式。如()：You will have to show your papers at the gate. 在大门口你得出示证件。We have had to postpone the meeting, due to the Chairwomans illness. 由于女主席生病了，我们不得不推迟开会。另外，have to 可以有分词、动名词、不定式等形式，而 must 则没有这些形式。如：Its annoying to have to get up early on Sundays. 星期日必须早起，令人恼火。You should offer to help without my having to ask. 你应该不用我请求就提供帮助。用于否定句时，must 的否定式 mustnt 意为“一定不要”“不允许”；而have to的否定式dont have to 意为“不必”(=neednt)。比较：You mustnt tell him about it你一定不要告诉他这件事。(可能是秘密) You dont have to tell him about it你不必告诉他这件事。(他可能知道了)推测用法是各类英语考试中最重要的考点，本文拟对此作一归纳。1.can / could用于表推测的用法(1) 从使用句型上看，can 通常只用于否定句或疑问句，一般不用于肯定句，而could 可用于肯定句、否定句和疑问句。两者没有时间上的差别，只是could 比 can 更委婉，更不确定。如：It cant couldnt be true. 那不可能是真的。What can could they be doing? 他们会在干什么呢?We could go there this summer. 今年夏天我们可能要去那儿。注：can 有时也用于肯定句中表示推测，主要用于表示理论上的可能性(即从理论上看是可能的，但实际未必会发生)，或表示“有时”之意。如：Even experienced teachers can make mistakes. 即使是有经验的教师也可能出错。She can be very unpleasant. 她有时很令人讨厌。(2) 从时间关系看，对现在或将来情况作推测，后接动词原形；对正在进行的情况作推测，后接 be doing 结构；对过去情况作推测，后接动词完成式。如：He could have gone home. 他可能已经回家了。He cant couldnt have understood. 他不可能理解了。Why does he know this? Can Could someone have told him about it? 他怎么知道? 会是哪个人告诉他了吗?(3) “could+完成式”除表示对过去的推测外，还有以下重要用法： 表示过去没有实现的可能性，常译为“本来可以”。如：I could have lent you the moneyWhy didnt you ask me? 我本来可以借这笔钱给你的。你为什么不向我提出? 用来委婉地责备某人过去应该做某事而没有去做，常译为“本来应该”。如：You could have helped him. 你本来应该帮助他的。 表示“差点儿就要”。如：I could have died laughing. 我差点儿笑死了。2. may / might用于表推测的用法表示推测，两者都可用，只是 might 比 may 语气更不确定，表示的可能性更小。(1) 在句型使用方面：两者均可用于肯定句和否定句，但用于疑问句时，may通常不用于句首，但可用于疑问句的句中（如特殊疑问句等），而might尽管可以用于疑问句的句首，但不算普通，通常会改用其他句式（如用could等）。如：He may might know the answer. 他可能知道答案。He may might not believe you. 他可能不会相信你。And who may might she be? 那么她会是哪一位呢？(2) 从时间关系看，对现在或将来情况作推测，后接动词原形；对正在进行的情况作推测，后接 be doing 结构；对过去情况作推测，后接动词完成式。如：He may might tell his wife. 他也许会告诉他妻子。He may might be writing a letter. 他可能在写信。She may might have read it in the papers. 她可能在报上已读到过此事。(3)“might+完成式”除表示对过去的推测外，还有以下重要用法： 表示过去某事可能发生而实际上却并没发生。如：It was really very dangerous. I might have killed myself. 那真的是太危险了，我差点没命了。A lot of men died who might have been saved很多人本来可以获救的却死了。 表示委婉的批评或责备。如：You might have made greater progress. 你的进步本来可更大一些的。You might at least have answered my letter. 你至少可以回我一封信嘛。3. must表示推测的用法must 表示很有把握的推测，其意为“一定会”“肯定会”，只用于肯定句，一般不用于否定句或疑问句。表示对现在或未来的情况作推测，后接动词原形；表示对过去情况的推测，接动词完成式。如：I must be the happiest woman on earth! 我一定是世界上最幸福的女人了。No, he must be lying. 不，他一定在撒谎(from )。He must have mistaken my meaning. 他一定误会了我的意思。4. should have done 的用法should have done只用于谈论过去情况，主要有两个用法：一是用于推测过去已经发生的情况，二是用于指本该发生而实际上未发生的情况。如：You should have told me so before. 你早就应该告诉我。He should have arrived by now. 此时他本该到了。Look at the time! We should have been at the theatre ten minutes ago. 瞧都什么时候了! 十分钟前我们就该到戏院了。5. need have done 的用法need have done结构主要用于否定句或疑问句，一般不用于肯定句。用于否定句时，表示本来不必做某事，但实际上却做了；用于疑问句时，用于询问某一过去动作的必要性。如：You neednt have hurried. 你当时实在不必那么匆忙。 She neednt have come in person a letter would have been enough. 她本不必亲自来写封信来就足够了。Need you have paid so 1. must 与 have to 的区别(1) 强调重点不同：两者都表示“必须”，但 must 侧重于说话者的主观看法，认为有必要或有义务去做某事；have to 则重于客观需要，含有“不得不”或“被迫”之意。(2) 时态形式不同：一般说来，must 只有现在时一种形式(在宾语从句中可以表示过去)，而 have to 则有多种时态形式。(3) have to 可以有分词、动名词、不定式等形式，而 must 则没有这些形式。如：I regret to have to trouble you again. 我很抱歉不得不再麻烦你一次。I only saw her in the evening, having to be away all day. 我因整天得外出，所以只能晚上见到她。(4) 否定式的含义不同：must 的否定式 mustnt 意为“不准”“不允许”；而 have to 的否定式 dont have to 意为“不必”(= neednt)。2. can 与 be able to 的区别(1) be able to 可用将来时态表示某人将来才具备的能力，而 can 不能用于将来时态。但若表示现在决定将来是否有能力做某事，可用 can。如：I can finish the article tomorrow. 我可以在明天写完这篇文章。(2) be able to 的过去式可表示某人过去某种具体的能力(即在某一具体场合做某事的能力，往往暗示经过努力才具备的能力)，但此时不能用 could)。如：He worked very hard and was able to pass his examinations. 他学习很努力，所以考试及了格。注：在否定句中 was (were) able to可用 couldnt代替。如：He worked very hard but wasnt able to couldnt pass his examinations. 他学习很努力，但考试却未能及格。(3) be able to 不仅有多种时态形式(通常不用于进行时或与 be going to 连用)，而且还可以与某些情态动词连用 (通常不与 can 连用)，甚至还可以有非谓语形式。如：He has not been able to go to school for a week. 他已有一周不能上学了。You might be able to persuade him. 你也许能够说服他。I hope to be able to do the work. 我希望能干得了这项工作。I regret not being able to help her. 我很遗憾未能帮助她。3. cant 与 may not 的用法区别(1) cant 有两个意思：它若表示能力，cant 意为“不能”；它若表示推测，cant 表示“不可能”。如：I cant finish it in time. 我不能按时完成。He cant be so rich. 他不可能那么富有。(2) may not 也有两个意思：它若表示许可，may not 表示“不许可”“不可以”；它若表示推测，may not 表示“可能不”。如：Visitors may not feed the animals. 参观者不得给动物喂食(from )。He may not be able to help but theres no harm in asking him. 他可能帮不了忙，但是求他一下倒也无妨。much? 你当时真须要付那么多钱吗? Need they have sold the farm? 他们那时非得把农场卖掉不可吗?表示许可的can / could / may / might / mustcan / could / may / might均可表示许可，只不过may较侧重讲话人的许可，而can较侧重客观情况的许可；could / might的语气比can / may更委婉、客气；在答语中表示允许别人做某事要can / may，不能用 could / might。如： Could Can, May, Might I use it? 我可以借用它吗? Yes, you can may. 可以。（不用 could / might）must表示必须作某事，其否定式mustnt表示“不可以”。如：We must not speak of it again. 我们再也不要谈这事了。will与would的用法表示意志或意愿：决心，愿意，好吗？We will do our best to save the child. 我们会尽力抢救这个孩子。I told her to stop crying, but she just wouldnt listen. 我叫她别哭,可她就是不愿听。注：表示请求、建议或征求对方意见时，用Would you? 比用Will you?更婉转。如：Will/Would you please keep the door open?请让门开着好吗？Will/Would you go with me?你愿意和我一起去吗?表示真理或习惯：惯于，总是Oil will float on water. 没总是浮在水面上。She will listen to music alone in her room for hours. 他独自在房间里听音乐，一听往往就是几小时。He would get up early when he lived in the country. 他住在乡下时总是早起。表示要求：一定，必须You will report to me afterward. 你稍后一定要向我报告。表示猜测：可能，大概This will be the house youre looking for. 这大概就是你找的那所房子了。I think he would accept the invitation. 我想他会接受邀请的。表示功能：能This auditorium will/would seat one thousand people. 这个礼堂能容纳一千人。would like表示愿意I would like to have a word with you. 我想同你说句话。Would you like a cup of tea? 请你喝杯茶好吗？would ratherthan宁愿也不愿I would rather fail than cheat in the examination. 我宁愿考不及格，也不愿意考试作弊。would与used to的比较(1) 两者都可以表示过去经常做某事，常可互换。如：When I was young I used to/would get up early. 我年青时经常早起。(2) 下列三种情况要用used to，不用would：强调与现在的对比时；在故事开头时；与be, stay, belong, live, like , think, know等状态动词连用时。如：He doesnt work hard as he used to. 他不像以前那样努力了。We used to swim every day when we were children. We would run down to the lake and jump in我们小时候天天游泳。我们会跑到湖边，跳进水里They used to live here, didnt they? 他们以前住在这里，是不是？(3) 与时间段或与表示“有时”意义的sometimes, at times, now and then, from time to time等连用时，宜用would。如：He would sit like that for hours. 他会像那样一坐就是几个钟。Sometimes the boys would play a trick on the teacher. 有时孩子们会戏弄老师。在陈述句中表示说话者给对方的承诺、决心、警告、威胁等。如：I shall write to you again at the end of the month. 月底我再给你写封信。You shall have it back next week. 下星期一定还你。He shall stay in bed. 他必须躺在床上。表示强制，用于法令、条约、规章中，意为“必须，应该”。如：Candidates shall remain in their seats until all the papers have been collected. 试卷完全收回后，应试人才能离开座位。在主语是第一、三人称的疑问句中征求对方意见：要不要？好吗？如：Shall I turn on the lights? 我开灯好吗?Shall he wait for you outside? 要不要他在外面等你?表示不可避免的某事：一定That day shall come. 那一天总会来的。表示“应该，应当”He should work harder. 他应该更加努力。You should help your mother with the housework. 你应该帮你母亲做家务。Crime should be punished. 犯罪应受惩罚。Should I wear a coat?我要穿大衣吗？表示“可能，该(=will probably) ”He should arrive soon他可能很快就到了。The train should have already left. 火车大概已经走了。表示“万一”If it should rain tomorrow, dont expect me. 万一明天下雨，就不要等我了。表示“竟然”Its strange that he should be late. 真奇怪，他竟会迟到。表示粗暴地拒绝一项建议、要求或指示 What time does the film start? 电影什么时候开始?How should I know? 我怎么知道? Anns very unhappy. 安非常不高兴。Why should I care? 这管我什么事? Could your wife help us in the office tomorrow? 你妻子明天能到办公室来帮帮我们吗?Why should she? She doesnt work for you. 她为什么就该去? 她又不是为你们工作的。should加完成式：should have done表示“本应该做某事，但事实上却没有做”；shouldnt have done表示“本不该做某事，但事实上却做了”。如：You should have got up earlier. 你本应该早点起的。You shouldnt have told him about it. 你本不该把这件事告诉他的。should与ought to的比较(1) 除表示“万一”“竟然”等只能用should外，表示“应该，应当”“可能”等，两者可互换，只是ought to的语气稍重。如：You ought to/should work harder than that. 你应当更努力地工作She ought to/should finish it by next week. 下星期她可能完成了。You ought to/should have told him about it earlier. 你本应该早点把这件事告诉他的。You oughtnt to/shouldnt have wasted time like that. 你本不该像那样浪费时间的。(2) should 强调主观看法，而 ought to 强调客观要求。如：We ought to go and see my mother in hospital tomorrow, but I dont think we will. 我们按理应当在明天去看看住院的母亲的，但我主认为我们不会去。(3) 在公告、须知或条例中，出于礼貌，常用should。如：You shouldnt run alongside the swimming pool. 不准在游泳池边奔跑。(4) 在虚拟语气中只能用should。如(from )：He suggested that I should go there. 他建议我去那里。(5) 注意ought to的否定式与疑问式。如：You ought not to do it. 你不应该做此事。Ought he to start now? 他现在该动身了吗？Yes, he ought (to) . 是的，该动身了。They ought to go now, oughtnt they?他们现在该走了，对吗？may,might表示允许和推测的用法1. may, might表示允许表示现在的允许时，若是请求别人允许自己做某事，两者均可用，但用might 语气更委婉；若是自己允许别人做某事，一般只用 may，而不用 might。如：May Might I come in? 我可以进来吗?“May Might I use your pen? ” “Yes, of course you may.” “我可以借用你的钢笔吗?”“当然可以。”(不能说Yes, you might.)注：在通常情况下，may 表示允许(请求允许或给予允许)时，总是针对“现在”或“将来”而言，若要表示已经给予或已经存在的允许，则通常不用 may，而用can：Nowadays, children can do what they like. 现在小孩子喜欢干什么就可以干什么。2. may, might表示推测两者都可用，只是 might 比 may 语气更不确定，表示的可能性更小。若推测现在的情况，后接动词原形；若推测正在进行的情况，后接动词进行式；若推测过去的情况，后接动词的完成式。如：He may might not be there. 他可能不在那里。He may might be waiting for someone. 他可能等人。They may might have seen him. 他们可能见到过他(from )。注：might 后接动词的完成式，除表示对过去的推测外，还可表示过去某事可能