would should could have done用法和区别

would should could have done用法和区别
would should could have done用法和区别

would/could/might/should have done等

用法和区别

一、在虚拟语气中的用法(情态动词都是过去时态!)

1. should have done:原本应该做某事,(否)shouldn't have done :原本不该做某事

2. ought to have done 原本应该做某事,(否) oughtn't to have done :原本不该做某事

注意:

ought to do 语气更强,常用于长辈对小辈的用语或某规则上的要求(严格的规则应用must ).

should do 可用语平辈朋友间,较为客气与口语化

3. need have done 原有必要做某事 (否) needn't have done 原本没必要做某事

注意:做情态动词,need的过去式仍然是need;做实意动词,need 的过去式是needed.

4.could have done 原本能够做某事

注意: couldn't have done 无虚拟语气的用法,只表推测,相当于 can't have done:过去不可能做了某事

5.might have done 原本可以做某事

注意: might not have done 无虚拟语气的用法,只表推测,相当于 may not have done:过去可能没有做某事

6.would have done原本会做某事

1. I would have told you all about the boy's story, but you didn't ask me.

二、对过去事情表推测的用法(情态动词用原型或过去式都可以,只是在说话者看来,可能性大小稍微有所不同而已)

1. must have done:过去肯定做了某事。不存在 mustn't have done 的形式。其否定或疑问形式须用 can(could)have done:“不可能做过某事”来表示:

Since the road is wet, it must have rained last night.

既然路是湿的,那昨天晚上肯定下雨了。

He can't/couldn`t have missed the way. I drew him a map.

他不可能迷路。我(当时)给他画了张图。

“The dictionary has disappeared. Who could/can have taken it?”词典不见了,(过去)谁可能把它拿走了?

2. may / might have done

may / might have done:过去可能做了某事,may 比 might 表示可能性稍大些。

may/might not have done过去可能没有做某事:

I can't find my keys. I may / might have left them at the school yesterday.

我找不到我的钥匙了。我可能昨天把他们落在学校了。

John may/might not have passed the exam; he looks very sad.

约翰可能没有通过考试。他看起来很忧伤。

注意:may/might have done表推测不能用于疑问句中,疑问句中表推测,一般用can/could have done sth.很可能做过某事

3. can/could have done 常用于(否定句)和(疑问句),间或(肯定句) Can/Could he have passed the exam ? 他可能通过了考试吗?

I think that he couldn’t/can't have gone abroad. I saw him just now.

我认为他不可能出国了。我刚才还看见他了。

注:表示推测过去某动作发生的可能性时,就表示的可能性程度而言,must 最大,could 其次,may 更次之,might 最小。例如:

“He must / could / may / might have heard of it from Mary.” “他肯定/很可能/可能/兴许(没准儿)已从玛丽那儿听说此事了。”

4.would have done:想必会/肯定会做某事

President Obama has canceled plans to set stronger air qualit y rules in the United States.The president said these plans wo uld have forced(想必会/肯定会迫使)

businesses to take action at a time when the country's econo my is weak. On Friday, president Obama ordered environment officials to halt a plan that would have affected(想必会/肯定会影响)companies, states and cities. All three would have requi red to reduce the amount of chemicals that case smog. Failure to do so, would have led to(肯定会/想必会导致)feder

al action.

(完整版)wouldshouldcouldhavedone用法和区别

would/could/might/should have done等 用法和区别 一、在虚拟语气中的用法(情态动词都是过去时态!) 1. should have done:原本应该做某事,(否)shouldn't have done :原本不该做某事 2. ought to have done 原本应该做某事,(否) oughtn't to have done :原本不该做某事 注意: ought to do 语气更强,常用于长辈对小辈的用语或某规则上的要求(严格的规则应用must ). should do 可用语平辈朋友间,较为客气与口语化 3. need have done 原有必要做某事 (否) needn't have done 原本没必要做某事 注意:做情态动词,need的过去式仍然是need;做实意动词,need 的过去式是needed. 4.could have done 原本能够做某事 注意: couldn't have done 无虚拟语气的用法,只表推测,相当于 can't have done:过去不可能做了某事 5.might have done 原本可以做某事 注意: might not have done 无虚拟语气的用法,只表推测,相当于 may not have done:过去可能没有做某事

6.would have done原本会做某事 1. I would have told you all about the boy's story, but you didn't ask me. 二、对过去事情表推测的用法(情态动词用原型或过去式都可以,只是在说话者看来,可能性大小稍微有所不同而已) 1. must have done:过去肯定做了某事。不存在 mustn't have done 的形式。其否定或疑问形式须用 can(could)have done:“不可能做过某事”来表示: Since the road is wet, it must have rained last night. 既然路是湿的,那昨天晚上肯定下雨了。 He can't/couldn`t have missed the way. I drew him a map. 他不可能迷路。我(当时)给他画了张图。 “The dictionary has disappeared. Who could/can have taken it?”词典不见了,(过去)谁可能把它拿走了? 2. may / might have done may / might have done:过去可能做了某事,may 比 might 表示可能性稍大些。 may/might not have done过去可能没有做某事: I can't find my keys. I may / might have left them at the school yesterday. 我找不到我的钥匙了。我可能昨天把他们落在学校了。 John may/might not have passed the exam; he looks very sad. 约翰可能没有通过考试。他看起来很忧伤。

英语虚拟语气语法归纳总结

虚拟语气: 表示说的话不是事实,不可能发生或者说可能性很小的情况,表达一种愿望、建议、假设。 if were/did, would do if had done, would have done if were to do/should do, would do 举例: If I were you, I would do nothing about it. If you had taken your teacher’s advice, you wouldn’t have made such a mistake. If it were to/ should rain tomorrow(表示降水率很低),they wouldn’t go shopping. 附注: 虚拟语气,条件状从倒装 状语从句中,去掉if,提前were/ had/ should 如:If I were you, I would give up. →Were I you, I would give up If you had taken the advice, you would have…. →Had you taken the advice, you would have… If the world shou ld come to an end,…… →Should the world come to an end…… 另外,without, but for, otherwise构成的条件状语从句中,也有含蓄的虚拟语气But for the popularization of electricity, we would lead a whole different life today. (popularization 普及,publicity 宣传) Without your help, I would have failed. We’ll go earlier, otherwise we wouldn’t get a seat.(表示可能性小)

could have done 用法

could have done 用法 1.表示主观猜测:即对已经发生动作或已经存在的状态作出主观上的猜测,通常可译为“可能(已经)”,有时需根据具体语境来翻译。如: Tom could have taken the money; he was here alone yesterday. 有可能是汤姆把钱拿走了,昨天他单独一个人在这里呆过。 We knew he couldn’t have paid for it, because he had no money. 我们知道不可能是他付了这笔钱,因为他没钱。 该用法也可将could换成can,但这只限于否定句和疑问句,因为can表推测时不用于肯定句(而could 可以用于肯定句)。如: Can he have left already? 他会已经离开了吗? They can’t have gone out because the light’s on. 他们不可能出去了,因为灯还亮着。 2.表示未曾实现的能力:即表示过去本来有能力可以做某事的,但实际上没有那样去做,通常译为“本来可以”“本来能力”等。如: The worst of it is that I could have prevented the accident. 最糟糕的是我本来可以防止这次事故的。 I could have passed my examination easily but I made too many stupid mistakes. 我本可以轻易通过考试,但我犯了太多不该犯的错误。 有时用于反语。如: You’ve broken my pen—thanks for nothing, I could have done that for myself. 你把我的笔给弄坏了—— 你得了吧,就那我自己也会弄。 3.表示未实现的可能性:即表示过去本来可能发生情况,而实际上没有发生,通常译为“本来可以”“本来可能”等。如: She could have been seriously injured. 她本来可能伤得很重的。 It’s difficult enough, but it could have been worse. 这事情够困难的了,本来可能会更糟呢。 有时也可根据语境译为“好在没有”“差点”,尤其是当谈论的是“不好”的情况时。如: She felt miserable. She could have cried. 她感到很痛苦,她差点哭了。 Why did you throw the bottle out of the window? Somebody could have been hurt. 你为什么把瓶子扔出窗外呢?好在没有砸伤人。 4.表示未曾实现的想法:即表示过去本来有做某事的打算或意图,但实际上没有实现,通常译为“本来可以”。如: I could have lent you the money. Why didn’t you ask me? 我本来可以借这笔钱给你的。你为什么不向我提出? I could have given you some hints, but I suppose you thought yourself too grand. 我本可以给你点提示的,但是我认为你太自负了。 5.表示未曾实现的选择:即表示过去本来可以有机会选择做某事,但实际上没有那样做,通常译为“本来可以”。如: You needn’t have typed it twice. You could have used a carbon. 你没必要打两遍的,你当时本可以用复写纸打。 You needn’t have walked up; you could have taken the lift. 你没必要走着上去,你本来可以乘电梯的。 6.表示批评或责备:即表示过去本来有责任或义务应该做某事的,但实际上却没有做成,含有批评和责备的意味,通常译为“本来应该”“本来可以”等。如: You could have started a little earlier. 你本可早点动身的。 You could have helped me—why did you just sit and watch? 你本来可以帮我一把嘛——为什么你只是坐在那儿观望呢? 7.表示可能达到的极限:表示即使人们尽力而为去做某事,但还是未能做成,通常用于否定句。如: I couldn’t have won, so I didn’t go in for the race. 反正我也赢不了,所以我就没有参加赛跑。

have和has用法的区别

have和has用法的区别: 在肯定句中,I,you,we,they,或复数做主语时用have,he,she ,it或单数作主语时用has。 在疑问句和否定句中无论什么人称作主语,都用have。 例如(肯定句):1. I have some paper. 2. You have some staples. 3. We have some stamps. 4. They have some sugar. 5. He has a ruler. 6. She has some balloons. 7. It has four legs. has some books. 例如(一般疑问句): 1. Do you have a bike 2. Do they have any salt 3. Does he have a bike 4. Does a rabbit have four legs ? 例如(否定句):1. I don’t have any rice . 2. We don’t have any salt . 3. He doesn’t have a pen . 4. She doesn’t have any envelopes . have和has用法的区别: 在肯定句中,I,you,we,they,或复数做主语时用have,he,she ,it或单数作主语时用has。 在疑问句和否定句中无论什么人称作主语,都用have。 例如(肯定句):1. I have some paper. 2. You have some staples. 3. We have some stamps. 4. They have some sugar. 5. He has a ruler. 6. She has some balloons. . 7. It has four legs. has some books. 例如(一般疑问句): 1. Do you have a bike 2. Do they have any salt 3. Does he have a bike 4. Does a rabbit have four legs 例如(否定句):1. I don’t have any rice . 2. We don’t have any salt . 3. He doesn’t have a pen . 4. She doesn’t have any envelopes . 【 have和has用法的区别: 在肯定句中,I,you,we,they,或复数做主语时用have,he,she ,it或单数作主语时用has。 在疑问句和否定句中无论什么人称作主语,都用have。 例如(肯定句):1. I have some paper. 2. You have some staples. 3. We have some stamps. 4. They have some sugar. 5. He has a ruler. 6. She has some balloons.

最新小升初英语语法零基础 can have done用法小结

小升初英语语法零基础:can have done用法小结 can have done can have done 通常只用于否定句和疑问句。用于否定句时表否定推断,推测肯定没做;用于疑问句时意为“难道真的做了吗”,表示怀疑。例如: Can he have done such a foolish thing? (= Is it possible …?) 他会做这样的傻事吗?(表怀疑) He can't have taken it home. 他不可能把它带回家了。(表不可能) could have done could have done 可用于肯定句、疑问句和否定句。用于肯定句既可以表示过去能够做而实际未做,有惋惜、遗憾或委婉批评之意,也可以表示对过去动作的推测;用于否定句和疑问句的情况与can have done 相同。例如: You could have done better, but you didn't try your best. 你本可以做得更好,但是你没有尽力而为。(表惋惜) This glass is cracked. Someone could have dropped it. 这个玻璃杯破了。可能是谁把它掉在地上了。(表推测过去) Could he have left the work unfinished?

他会丢下工作不干了?(表怀疑) He couldn't have checked out so early. 他不可能这么早就离开了。(表不可能) 注意:can't have done 的语气比 couldn't have done 要强一些。例如:He can't have been to that town. 他根本不可能去过那座城市。(语气略强) The measurement couldn't have been wrong. 测量不可能出错了吧。(语气稍弱)

Have与 has的用法及区别

Have与has的用法及区别 have与has都是“有”的意思,但二者用法是有区别的. 在陈述句中,当主语是单数第三人称(he、she、it)时,句子的谓语是“有”时,用has;当主语是其他人称(I、you、we、they)时,句子的谓语是“有”时,用have. 例句: I \ You have an apple . We\They have some apples . He\She has a pen . 但是,在疑问句中,当主语是就单数第三人称提问或否定句时用助动词does 和does not (doesn't),然后把has 变成have 如果不是第三人称,助动词就是do ,否定式do not (don't).特殊疑问句回答照样,该是has 还是has 该是have 还是have 但是当一般疑问句以do或does开头的时候,只能回答do don’t 或者does doesn't 例句: Do you have a book yes ,I do /No ,I don't What does a cat have the cat has a , He doesn’t have any coffee. 就是第二种:have本身也可以作为助动词,(作为完成时里的助动词)本身无词义,和do 一样,has 就相当于does 在单三情况下用,主要用于构成各种时态、语态、语气以及否定和疑问结构.(那此时的have还是has就要看具体的人称而定)完成时态是have/had + done (过去分词的形式) I have finished my work, she has finished her work have you finished your work? Has she finished her work?在一般疑问句里回答直接用have/has yes,I have/ No ,I haven't Yes,she has/ No,she hasn't(因为这里have/has是助动词)

不定式完成式to have done用法

情态动词+have done用法 1. Something may have happened to her. 她可能发生了什么事情。 She might have had an accident. 她或许遭受了意外. So she must have taken that too. 因此,她肯定把它也带走了。 1) 这三句话都用了“情态动词+不定式的完成时”,表示对发生过的事作某种猜测、推测。 (1) must have done 可用来对某件过去的事情作肯定推测,表示“一定已经,想必已经”做过某事,用于肯定的陈述句中。否定句中用can't have done。 She must have received the parcel, I sent it by registered post. 她一定已经收到包裹了,我是用挂号寄的。 (2) may have done, might have done, could have done “可能做过某事”,就语气而言could have done 所表的可能性更小些。 He may / might / could have left by nine. 他可能于九点前已离去。 (3) should have done / ought to have done表示“本该做某事”但实际未做。 I should / ought to have left London before nine but I didn't. 我本该在九点以前离开伦敦,但是我没有。 (4) shouldn't have done / oughtn't to have done 表示“本不该做事”,但实际上又做了。 He shouldn't / oughtn't to have left London before nine but he did. 他本不该在九点前离开伦敦,但是他离开了。 (5) can't / couldn't have done 表否定推测,“不可能做过某事”。 She can't / couldn't have gone to bed, for the light in her room is still on. 她不可能上床睡觉了,因为她房间的灯还亮着。 (6) could have done 可表示客观上“本来能做某事但实际上没做”。 He could have finished the work in time but he didn't work hard. 他本来可以按时干完活的,但他没有卖力。 (7) needn't have done 表示客观上“本不必做某事但实际上又做了”。 I needn't have gone to the office yesterday (but I went there). 昨天我没必要去办公室(但我却去了)。 (8) might have done 还可表示过去“本可能发生但实际上没有发生的动作”。用于表示说话人对已发生的事提出批评或意见。 He might have given more help, even though he was very busy. 即使他很忙,也可以多帮点忙。 情态动词+ 动词完成式即“情态动词+ 动词完成式即“情态动词+ have + done”,表示对过去行为或动作进行推测、评论或判断。这个结构是近几年高考情态动词的重点和难点。 一、在虚拟语气中的用法 1. should have done 表示“过去本应该做某事却未做。”其否定结构shouldn't have done 表示“过去本不该做某事却做了。” 2. ought to have done 表示“过去本应该做某事却未做。”其否定结构oughtn't to have done 表示“过去本不该做某事却做了。” 3. need have done 表示“过去本有必要做某事却未做。”其否定结构needn't have done 表示

Have 和has的用法

Have 和has的用法 谓语动词have表示“有”,有两种形式:have和has,前者用于第一人称(I、we),第二人称(you)和第三人称(they),后者用于第三人称单数(he、she、it)或单数名词。 have/has句型与there be句型的比较:两者都表示“有”,但用法不同。前者表示所属关系,即表示“某人或某物有什么”,而后者表示存在,表示“某地有什么”。 一、用have, has填空。 1. I _ some red ink. 2. His mother an old house. 3. You _ two big eyes. 4. Their parents many friends. 5. My brother __ a nice T-shirt. 6. The doctors __ white clothes. 7. He and she __ some bananas. 8. Look, the child __ some sweets. 9. Our school twelve classroom. 10. The students many books. 11. His sister a new bike. 12. Their English teacher some nice photos.

13. Your brothers______a new bike. 14. LiMing’s mother_________two big eyes. 15. Jenny and Danny__________two black pens. 16. The dogs_______some meat in its mouth. 17. The students of Class One________a football. 18. Mary_________an old doll. 19. They _________some soup for supper. 20. Our school________a big library. 21.I a cat. 22.He a dog. 23. She long hair. 24. We a big house. 25. They a happy family.

英语虚拟语气类型用法

二、虚拟语气的判断: 1. if 条件状语从句中虚拟语气的判断。if 条件状语从句有真实条件句和非真实条件句。假设条件可以实现的句子为真实条件句,反之为非真实条件句,要用虚拟语气。其形式分为以下三种: (1) 与过去事实相反的假设。结构为:从句的谓语动词用“had + 过去分词”,主句用“should (would, could, might) + have + 过去分词”。例如: If it had not rained so hard yesterday, we could have played tennis. 如果昨天没有下大雨,我们就能玩网球了。 (2) 与现在事实相反的假设。结构为:从句的谓语动词用过去式,系动词用were,主句的谓语用“should (would, could, might) + 动词原形”。例如: If I were in your position, I would marry her. 如果我是你,我就娶她为妻。 (3) 与将来事实相反的假设。结构为:从句的谓语动词用“should (were to) + 动词原形”,主句用“should (would, could, might) + 动词原形”。例如: If you should miss the chance, you would feel sorry for it. 如果你错过了这次机会,你会难过的。 2. 宾语从句中的虚拟语气。 (1) wish后接宾语从句中的虚拟语气:根据从句的意义来判断。 A: 表示与现在和将来事实相反的愿望,从句谓语动词用过去时态。例如: I wish they were not so late. 要是他们来得不是这么晚就好了。 B: 表示与过去事实相反的愿望,从句谓语动词用过去完成时态。例如: I wished he hadn't done that. 我真希望那件事不是他做的。 (2) 表示“要求、建议、命令”等动词后面的宾语从句中的虚拟语气。用于此结构的动词有:advise, direct, agree, ask, demand, decide, desire, insist, order, prefer, propose, request, suggest 等。从句的谓语动词用“should + 动词原形”,其中should 可以省去。例如: I insisted that he (should) go with us. 我坚持让他和我们一起去。 注意:当insist 表示“坚持认为”、suggest表示“表明,显示”时,不用虚拟语气。例如:

have_和has的用法

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高中英语虚拟语气的用法

高中英语虚拟语气的用法 一、考查虚拟语气在条件从句中的用法 时间从句谓语形式(be用were不可改变)主句谓语形式 将来一般过去时(be用were) would/should/might/could+动词原形 现在一般过去时(be用were) would/should/might/could+动词原形 过去现在完成时would/should/might/could+had done (1)If he my advice, he wouldn' t have lost his job. A. followed B. should follow C. had followed D. would follow (2)If we the other road, we might have arrived here in time for the meeting. A. taken B. had taken C. took D. have taken (3) -John went to the hospital alone. -If he me about it, I would have gone with him. A. should tell B. tells C. told D. had told 二、考查特殊句型中的虚拟语气 英语中需要使用虚拟语气的特殊句型不多,主理有以下类: 1.“倒装”类虚拟语气 当虚拟条件句中含有were, should, had时,有时可将引导虚拟条件句的连词if省略,而将从句中的were,should, had提到句首,构成倒装形式的虚拟语气。如: If he were here, she would agree too.→Were she here, she would agree too.如果她在这里,她也同意的。. If it should rain tomorrow, we should have to put off the match. →Should it rain tomorrow, we should have to put off the match.假若明天下雨,我们只好推迟这场比赛。 If we had found him earlier we could have saved his life.→Had we found him earlier we could have saved his life. 要是我们当时早点找到他的话,我们就可以救活他。 注意,如果条件从句的谓语为否定式,其中的否定词not应置于主语之后,而不能与were,should, had等缩略成Weren' t, Shouldn' t, Hadn'场置于句首。如:我如不是警告了你,你就可能丧命了。 正: If I hadn' t warned you, you could have been killed. 正: Had I not warned you, you could have been killed. 误: Hadn' t I warned you, you could have been killed. 另外,有时省略if后提前到句首的had可能不是助动词,而是实义动词。 如: Had I time, I would go with you.假如我有时间,我就同你们一起去。句中的had不是构成过去完成时的助动词,而是表示“有”,如果不省略if ,完整形式为:If I had time, I would go with you. (1) Had I known about this computer program, a huge amount of time and energy____. (2010浙江卷) A.would have been saved B. had been saved C. will be saved D. was saved (2) fired, your health care and other benefits will not be immediately cut off. (2006湖北) A. Would you be B. Should you be C. Could you be D. Might you be 2.“宁愿”类虚拟语气 这里说的“宁愿”主要是指would rather。当它后接句子的时候,句子的谓语通常要用虚

“could +have+过去分词”的10种用法

“could +have+过去分词”的10种用法 一、表示主观猜测 即对已经发生动作或已经存在的状态作出主观上的猜测,通常可译为“可能已经…”,有时需根据具体语境来翻译。如: We could not have heard them because of the noise from the river. 由于有河水声我们不能听见他们的话。 Tom could have taken the money; he was here alone yesterday. 有可能是汤姆把钱拿走了,昨天他单独一个人在这里呆过。 We knew he couldn’t have paid for it, because he had no money. 我们知道不可能是他付了这笔钱,因为他没钱。 【说明】该用法也可将could换成can,但这只限于否定句和疑问句,因为can表推测时不用于肯定句,而could可以用于肯定句。如: Can he have left already? 他会已经离开了吗? They can’t have gone out because the light’s on. 他们不可能出去了,因为灯还亮着。 二、表示未曾实现的能力 即表示过去本来有能力可以做某事的,但实际上没有那样去做,通常译为“本来可以、本来能够”等。如: The worst of it is that I could have prevented the accident. 最糟糕的是我本来可以防止这次事故的。 We could have got in for nothing—nobody was collecting tickets. 我们本可以不买票就进去—根本没人收票。 I could have passed my examination easily but I made too many stupid mistakes. 我本可以轻易通过考试,但我犯了太多不该犯的错误。 有时用于反语中。如: You’ve broken my pen—thanks for nothing, I could have done that for myself. 你把我的笔给弄坏了——你得了吧,就那我自己也会弄。 三、表示未曾实现的可能性 即表示过去本来可能发生的情况,而实际上没有发生,通常译为“本来可以、本来可能”

英语虚拟语气用法总结

英语虚拟语气用法总结 1、表示与现在事实相反的情况: 从句:主语+过去时 主句:主语+should/would/could/might+do eg: 1.If I were you,I would take an umbrella. 如果我是你,我会带把伞.(事实:我不可能是你) 2.If I knew his telephone number,I would tell you. 如果我知道他的电话号码,我就会告诉你.(事实:不知道) 2、表示与过去事实相反的情况 从句:主语+had+done 主句:主语+should/would/could/might+have done eg: 1. If I had got there earlier,I should/could have met her.如果我早到那儿,我就会见到她. (事实:去晚了) 2.If he had taken my advice,he would not have made such a mistake.如果他听我的劝告的话,就不会犯这样的错误了.(事实:没有听我的话) 3、表示对将来情况的主观推测 从句:主句 ①if+主语+were to do :①主语+should/would/could/might+do ②if+主语+did/were ②主语+should/would/could/might+do ③if+主语+should+do ③主语+should/would/could/might+do eg: 1.If he should come here tomorrow,I would talk to him.

have和has-用法

have与has都是“有”的意思,但二者用法是有区别的. 在陈述句中,当主语是单数第三人称(he、she、it)时,句子的谓语是“有”时,用has;当主语是其他人称(I、you、we、they)时,句子的谓语是“有”时,用have. 例句:I \ You have an apple . We\They have some apples . He\She has a pen . 但是,在疑问句中,当主语是就单数第三人称提问或否定句时用助动词does 和does not (doesn't),然后把has 变成have 如果不是第三人称,助动词就是do ,否定式do not (don't).特殊疑问句回答照样,该是has 还是has 该是have 还是have 但是当一般疑问句以do 或does开头的时候,只能回答do dont 或者does doesn't 例句: Do you have a book yes ,I do /No ,I don't What does a cat have the cat has a , He doesnt have any coffee. 就是第二种:have本身也可以作为助动词,(作为完成时里的助动词)本身无词义,和do 一样,has 就相当于does 在单三情况下用,主要用于构成各种时态、语态、语气以及否定和疑问结构.(那此时的have还是has就要看具体的人称而定)完成时态是have/had + done (过去分词的形式) I have finished my work,she has finished her work have you finished your work?has she finished her work?在一般疑问句里回答直接用have/has yes,i have/ No ,i haven't Yes,she has/ No,she hasn't(因为这里have/has是助动词) have 是动词原形i have,we have,you have,they have,to have...

(完整版)couldhavedone用法详解

could have done 用法详解 1.表示主观猜测:即对已经发生动作或已经存在的状态作出主观上的猜测,通常可译为“可能(已经)”,有时需根据具体语境来翻译。如: Tom could have taken the money; he was here alone yesterday. 有可能是汤姆把钱拿走了,昨天他单独一个人在这里呆过。 We knew he couldn’t have paid for it, because he had no money. 我们知道不可能是他付了这笔钱,因为他没钱。 该用法也可将could换成can,但这只限于否定句和疑问句,因为can表推测时不用于肯定句(而could可以用于肯定句)。如: Can he have left already? 他会已经离开了吗? They can’t have gone out because the light’s on. 他们不可能出去了,因为灯还亮着。 2.表示未曾实现的能力:即表示过去本来有能力可以做某事的,但实际上没有那样去做,通常译为“本来可以”“本来能力”等。如: The worst of it is that I could have prevented the accident. 最糟糕的是我本来可以防止这次事故的。 I could have passed my examination easily but I made too many stupid mistakes. 我本可以轻易通过考试,但我犯了太多不该犯的错误。 有时用于反语。如: You’ve broken my pen—thanks for nothing, I could have done that for myself. 你把我的笔给弄坏了——你得了吧,就那我自己也会弄。 3.表示未实现的可能性:即表示过去本来可能发生情况,而实际上没有发生,通常译为“本来可以”“本来可能”等。如: She could have been seriously injured. 她本来可能伤得很重的。 It’s difficult enough, but it could have been worse. 这事情够困难的了,本来可能会更糟呢。 有时也可根据语境译为“好在没有”“差点”,尤其是当谈论的是“不好”的情况时。如:She felt miserable. She could have cried. 她感到很痛苦,她差点哭了。 Why did you throw the bottle out of the window? Somebody could have been hurt. 你为什么把瓶子扔出窗外呢?好在没有砸伤人。

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