by the time用法15041

细心整理By the time 用法详解 by the time意为“到时候为止”，是一个介词短语，在句中常常起连词作用，引导时间状语从句。它的主要用法如下： 1. 假如从句中的谓语动词是一般过去时，那么主句中的谓语动词通常用过去完成 时，表示“截止到从句动作发生时，主句动作已经完成，即过去的过去”。例如： By the time he returned home，the rain had stopped. By the time I got to the station，the train had already gone。 2. 假如从句中的谓语动词为一般此时此刻时/或此时此刻完成时表示将来，那么主句中的谓语动词常为将来完成时，表示“截止到将来某一时间为止，主句动作将已经完成”。 By the time you get back，I shall have finished the work. By the time I graduate next year, I will have lived here for 5 years. By the time of next term , we will have learned 3000 words. 3. 假如主句动作不强调已经完成，只是说明某个时候的状况，主句是be的系表形式或者是表示像know, find, believe等表示认知的持续性动词，那么往往用一般时态，不用完成时态。此时主句不用完成时，而应依据实际须要选用适当的时态，此时by the time相当于when。 例如： He was out of breath by the time he reached the top. By the time the bus came，so many people were waiting that it was a free fight to get on it. 公共汽车来的时候，等车的人很多，成了一场挤车的混战。 By the time he went abroad, he was fourteen.出国那年他14岁。 By the time the war was over , death and suffering were to be seen everywhere. 在斗争完毕的时候，到处可见死亡和饥饿。 这里没有“死亡和饥饿”已经完成的意思，只是描述当时这个时间点的状况。所以用过去时。 稳固练习： 1. 2005天津卷 By the time Jane gets home， her aunt _for London to attend a meeting. A. will leave B. leaves C. will have left D. left 2. By the time you have finished this book, your meal _ cold.(2012四川卷) A. gets B. has got C. will get D. is getting 3. 2009北京卷 When I talked with my grandma on the phone， she sounded weak， but by the time we _ up， her voice had been full of life. A. were hanging B. had hung C. hung D. would hang 4. Did you see Xiao Li at the party？ No，_by the time I arrived. A. shed left B. shes left C. she was left D. she must leave 5. By the time I saw the angry expression on his face，I_ what I had to face. A. knew B. have known C. would know D. had known 6.2008四川卷 The telephone_， but by the time I got indoors，it stopped. A. had rung B. was ringing C. rings D. has rung 7.2008山东卷 By the time he realizes he _into a trap， itll be too late for him to do anything about it. A. walks B. walked C. has walked D. had walked 情态动词用法总结如下表情态动词用 法否认式疑问式简答式can1.表示实力体力，技能2.允许或许可口语中常用3.可能性表推想，用于否认句或疑问句中4.用于确定句表示理论可能性can not / cannot /cant doCando?Yes,can.No,cant.couldcouldnt domay可以问句中表示请求可能，或许表推想祝愿用于倒装句中may not do Maydo?Yes,may. No,mustnt/cant.mightmight not doMightdo?Yes,mightNo,might not.must必需，应当表主观要求确定，想必确定句中表推想must not/mustnt doMustdo? Yes,must.No,neednt/dont havehave to只好，不得不客观的必需，有时态和人称的变更dont have to doDohave to do?Yes,do. No,dont.ought to应当表示义务责任，口语中多用shouldought not to/oughtnt to doOughtto do?Yes,ought. No,oughtnt.shall用于一三人称征求对方看法用于二三人称表示许诺、叮嘱、警告、威逼等shall not/shant doShalldo?Yes,shall. No,shant.should应当，应当表义务责任本该含有指责意味should not/shouldnt doShoulddo?will意愿，决心请求，建议，用在问句中would比拟委婉will not/wont doWill/Woulddo?Yes,will. No,wont.wouldwould not/wouldnt dodare敢常用于否认句和疑问句中dare not/darent doDaredo?Yes,dare.No,darent.need须要，必需常用于否认句和疑问句中need not/neednt doNeeddo?Yes,must. No,neednt.used to过去时时此时此刻已不再used not/usednt/usent to dodidnt use to doUsedto do?Diduse to do?Yes,used. No,use(d)nt. Yes,did. No,didnt.学法提炼must have done表示主观上对过去已经发生的行为进展推想，意为“想必，准是，必需做了某事”; may/might have done表示对过去已发生行为的推想，意为“很有可能”；canhave donecannot have done1) could have done 用于对过去可能性的推断，意为“可能”，在确定句中，指“某事可能是事实或可能会发生”；用于疑问句或否认句，表示对过去状况的疑心、否认或惊异；2could have done 意为“原来可以；差点就要”，指“某事可能发生但事实上未发生”常用于虚拟语气，表示惋惜、缺憾等；might have done表示“原来可能，但事实上没有发生的事情”。另外，还可以表示“原来应当或可以做某事”之意，含有略微的指责语气。should/ought to have done1) 用于确定句时，表示本该做某事，而事实上未做；用于否认句时，那么表示不该做的事反而做了; 2) 用于对过去的推断，说话人认为“按理应当、理应如此”，说话人不能确定，只是摸爽性地得出结论，语气宛转；3) 对已发生的事表示“惊异、悲观、生气”等心情。neednt have done表示做了原来不必去做的事。留意：didnt need to do表示“没必要做而事实上也没有做某事”will/would have done用于推想过去，意为“想必、可以确定”，指“说话人确信某事已发生，但并不确知”，并用于二、三人称：1假如以此时此刻为时间点，可以用“will have done”；2假如以过去为时间点，只能用“would have done”；3will have done也用于推想将来某个时间前已经完成。If they _ to do this work, he might do it some other way.A. wereB. shouldC. willD. can2. I was told yesterday that the company _ me to Rome next week for a business conference.A. should have sentB. were going to sendC. should be sendingD. should send3. Lets take a walk, _? A. will we B. dont we C. do we D. shall we4. He was a good swimmer so he _ swim to the river bank when the boat sank.A. could B. might C. should D. was able to5. I went to the doctors yesterday, I had to wait for half an hour before he _ see me.A. can B. may C. might D. could6. - _ this book be yours?- No, it _ not be mine. It _ be his.A. Can, must, mayB. May, might, mustC. Can, may, must D. Must, can, may7. - We didnt see him at the lecture yesterday.” - “He _ it.”A. mustnt attend B. cant have attended C. would have not attended D. needed have attended8. They _ the plane, or perhaps they have been prevented from coming for some reason.A. can have missed B. may have missedC. can have lost D. may have lost9. Since the ground is white, it _ last night.A. had snowed B. must have snowedC. must be snowing D. must have been snowing10. You must be fifty, _?A. mustnt you B. neednt you C. arent you D. maynt you11. You must have seen him off yesterday, _?A. havent you B. didnt you C. mustnt you D. neednt you12. - That must be a mistake.- No .it _ be.A. cant B. isnt able to C. can D. was able to13. He had known the matter before you told him, so you _ have told it to him.A. mustnt B. cant C. neednt D. shouldnt14. How _ so?A. dare you to say B. dare you say C. do you dare say D. dare to say15. You are their teacher. You _ care of them.A. should to take B. might to take C. ought to take D. need to take16. She is studying medical science now but she _ a lawyer.A. used to be B. would be C. were Youreturn the book now. You can keep it till next week if you like.A. cantB. mustntC. needntD. may not2.I wish Ito the moon one day.A. can flyB. an able to flyC. could flyD. was able to fly3.If my lawyerhere last Saturday, heme from going.A. had been; would have preventedB. had been; would preventC. were; would preventD. were; would have prevented4.If itfor the snow, wethe mountain yesterday.A. were not; could have climbedB. were not; could climbC. had not been; could have climbedD. had not been; could climb5.Without electricity human lifequite difficult today.A. isB. will beC. would have beenD. would be6.Jennyhave kept her word. I wonder why she changed her mind.A. mustB. shouldC. needD. would7.Welast night, but we went to the concert instead.A. must have studiedB. might studyC. should have studiedD. would study8.Could I borrow your dictionary?Yes, of course you.A. mightB. willC. canD. should9.If he, hethat food. Luckily he was sent to the hospital immediately.A. was warned; would not takeB. had been warned; would not have takenC. would be warned; had not takenD. would have been warned; had not taken10.I told Sally how to get here, but in fact, Iher, for she had been here a short time before.A. neednt tellB. didnt need to tellC. neednt have toldD. didnt need to have told