whether和if的用法区别

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1、 whether和if的用法区别 　　whether与if作“是否”讲，在用法上有相同之处，也有不同之处。 　　一、相同之处。 　　1.whether和if都能引导宾语从句，常置于see,ask,learn,tell,wonder,doubt,find out等动词之后。 　　如：He asked me whether/is I could help him. I want to know whether/if he lives there. 　　2.whether和if都可用it作形式主语从句中。如： it's uncertain whether/if he'll com

2、e this evening. 　　3.在be uncertain/doubtful之后，常用whether引导宾语从句，有时也可以用if，如： We are uncertain whether/if Mary will come. 　　二、不同之处。 　　1.whether可置于句首引导主语从句，而if不能。如： ___the 2000 Olympic Games will be in Beijing is not known yet. A.whether B.If C.Whether D.That 答案是C。 　　2.whether可用在介词之后，引导宾语从句，而If则不能

3、。如： Success depends on whether we make evough effort. 　　3.whether可引导表语从句，if则不能。如： The puestion is whether it is not worth doing. 　　4.在名词之后引导同位语从句时，用whether而不用if。如： The question whether the students answered correctly should be decided by the teacher. 　　5.whether后可接不定式，而if不能。如： Please tell us w

4、hether to go or stay here. 　　6.在有些动词（如discuss）之后，只能用whether，而不用if引导宾语从句。如： We discussed whether we should close the shop. 7.在引导否定概念in宾语从句时，只能用if，而不用whether.如：he asked me if I hadn't finished my work. 英语时态         一般现在时表示现在、经常或习惯的动作或状态和普遍现象、常识或客观真理；一般过去时用于过去某一时间内发生的或过去习惯性的动作或状态；一般将来时表示将要发生的动作或存

5、在的状态，将来打算做的事情；现在完成时表示过去发生的动作造成目前的结果和对现在造成的影响或表示从过去延续至今的动作、状态和习惯等；将来完成时表示将来某时之前业已完成或发生的事情；过去完成时表示过去某时间之前已经发生的动作或状况，即过去的过去。注意每一种时态与其他时态的交叉使用情况。英语共有十六种时态，其表现形式如下(以study为例)： 一般时 进行时 完成时 完成进行时 现在 study studies am studying is studying are studying have studied has st

6、udied have been studying has been studying 过去 studied was studying were studying had studied had been studying 将来 shall study will study shall be studying will be studying shall have studied will have studied sh

7、all have been studying will have been studying 过去将来 should study would study should be studying would be studying should have studied would have studied should have been studying would have been studying 但考试中出现的一般有以下几种。 第一节 一般现在时 一、表

8、示一般性或经常发生的动作或状态 二、表示习惯性动作和状态或普遍的现象或常识 三、表示客观事实、客观规律和客观真理。在宾语从句中，即使主句的谓语动词用了过去时，只要从句表示的是客观真理，从句的谓语动词也要用一般现在时 四、祈使句必须用动词原形，其否定结构用 整理为word格式 “don`t＋动词原形”，如：Go and fetch some water. ／ Don`t do that. 五、在反义疑问句中，如果主句用肯定句，那么，反问句用否定形式；如果主句用否定形式，那么，反问句就用肯定形式。而且前后在时态上要一致。但祈使疑问句用won`t you?进行反问。如

9、：See a film tonight, won`t you? 注：① 祈使句后边可用附加疑问句，以加强语气。如果祈使句用肯定形式，附加疑问句用否定形式；如果祈使句用否定形式，附加句用肯定形式；如： Come here next Sunday, won`t you? ／ Don`t tell it to anyone, will you? ② 但如果祈使句的前一句有了表示强烈肯定的语言环境，即使祈使句用了肯定形式，其附加成分也可以用“will you”(表示肯定，如果是在口语中用降调)。如：Give me the book, will you? 第二节 一般过去时 一、一般过去时

10、主要表示过去某一时刻发生的动作或情况，句中通常有表示过去某一时刻的状语 a day ago, last week, in 1996, during the night, in anceint times等，表示“过多少时间之后”用after, 但在现在完成时中用in, 如in the past few years等 第三节 一般将来时 一、一般将来时表示将要发生的动作或状况 二、在表示时间和条件的状语从句中，一般现在时代替一般将来时。这些时间副词有when, as soon as等，表示条件的连词有if,as long as等 三、一些表示方向及变化的瞬间动词可用进行时或现在时

11、表示将要发生的动作 We leave (are leaving) for California the day after tomorrow.我们(计划)后天动身去加利福尼亚州。 May I have your attention please. The plane for Wuhan is about to take off.请注意，飞往武汉的飞机就要起飞了。 四、另外，“be +to ＋动词原形”也可表示打算做的事，还可表示责任、意向和可能性 You are to follow the doctor’s advice.你应遵从医嘱。 No shelter was to be

12、seen.找不到避难处。 第四节 现在完成时 一、现在完成时的构成式是have(has)＋动词的ED分词 二、现在完成时表示到现在为止的一段时间内发生的情况或动作，强调的是对现在的影响，可能是已完成的动作，也可表示多次动作的总和，或习惯性的行为和持续的动作 三、如果句中有表示到现在为止这段时间的状语时，用现在完成时，这些时间状语有 now, today, this week, this month, this year，现在完成时不和表示具体的时间状语连用，如yesterday, last year等，但可以和always, before, just, in／durin

13、g the past(few weeks, years, fifty years)连用，这时in表示“过去多少时间”，不能用after 四、在有already, as yet, yet, ever, just, never 这类副词作状语的情况下，用现在完成时 五、有“since＋时间点，for＋一段时间”引导的状语时，主句谓语用现在完成时态 11) Jekyll Island has been one ［A］ of Georgia’s state ［B］ parks ［C］ in ［D］ 1954. 12) He is ［A］ in this country now ［B］

14、for five years， but he makes ［C］ no attempt to speak ［D］ our language. 13) The Browns ［A］ are living a hard ［B］ life because Mr. Brown has been unemployed ［C］ since ［D］ half a year. 六、现在完成时用于将来的情况，即主语为一般将来时，时间和条件从句中的谓语用现在完成时(而不能用将来完成时)表示将来某时完成的动作 整理为word格式 第五节 将来完成时和过去完成时 一、将来完成时表示将来某时业已发

15、生的动作和情况，或已经存在的状态 二、过去完成时表示在过去某一时刻之前业已发生了的动作或现象，句中通常会出现有表示过去某一时刻的时间状语 第六节 进 行 时 态 一、现在进行时表示现在或现阶段进行的动作，但也和always, constantly, forever等频度副词连用表示一个经常进行的动作或现在存在的状态 二、瞬间动词和一些表示状态及感觉的动词一般不用进行时，而用一般现在时或一般过去时代替。这些动词包括：appear(显然), arrive, be, come, desire, go, find, hate, hope, join, know, leave, li

16、ke, love, join, possess, start, sail, see, suggest, taste, think(认为), understand等，类似的动词还有belong to， consist of，seem(似乎)等 三、过去完成进行时 过去完成进行时表示到过去的某一时间点或某一时间段里一直在进行的动作或行为 5) They received the parcel that they for a long time. ［A］ expected ［B］ have expected ［C］ had been expecting ［D］ had expected

17、 There is a wellknown incident in one of Moliere′s plays, where the author makes the hero express unbounded delight on being told that he had been talking prose during the whole of his life.(93年翻译) 四、例题解析 1) D错。slow只有作为不及物动词用时才与up或down连用，表示“慢慢向上”或“慢慢向下”。所以我们说，这里的slow是动词而不是形容词，应将动词slow后边加上“ing”，

18、改为(is) slowing down，构成现在进行时。 2) C错，改为are。 3) A错，改为saw。 4) D错，改为are。 5) C为正确答案。 英语高考专题复习讲与练（17）反意疑问句 反意疑问句是英语四大问句之一，它是由一个陈述句加上一个短问句而构成的。反意疑问句的基本构成形式是：陈述句+动词（肯定或否定）+主语？如： ①She often has lunch at school, doesn’t she? ②You don’t like sports, do you? 使用反意疑问句要注意以下若干对应规则： 一、 反意疑问句中问句部分的动词与

19、陈述部分的动词在语气上成相反的对应关系，即： 肯定+否定？ 否定+肯定？如： ①You can’t do it, can you? ②They are very late for the meeting, aren’t they? 二、 反意疑问句中问句部分的动词与陈述部分的动词种类要对应一致。如： ①He has supper at home every day, doesn’t he? （不能用hasn’t he?） ②They have known the matter, haven’t they? （不能用don’t they?） 三、 反意疑问句中问句部分的动

20、词在时态上应和陈述部分的时态一致。如： ①They will go to town soon, won’t they?（不能用don’t they?或 aren’t they?） ②He works very hard, doesn’t he?（不能用didn’t he?或won’t he?） 四、 反意疑问句的陈述部分含有由un-, im-, in-, dis-, 等否定意义的前缀构成的词语时，陈述部分要视为肯定含义，问句部分用否定形式。如： 整理为word格式 ①Your father is unhappy, isn’t he?（不能用is he?） ②T

21、he man is dishonest, isn’t he? （不能用is he?） ③It is impossible to learn English without remembering more words, isn’t it?（不能用is it ?） 五、反意疑问句的陈述部分带有little, few, never, hardly, seldom等否定意义的词时，问句部分用肯定式。如： ①She never tells a lie, does she?（不用doesn’t she?） ②He was seldom late, was he?（不用wasn’t he?

22、） 六、反意疑问句的陈述部分为I am……时，问句部分习惯上用aren’t I？表示。如： I am a very honest man, aren’t I? 七、反意疑问句的陈述部分为I(We) think(believe, suppose, consider) + that从句时，问句部分的动词及主语与that从句内的动词和主语保持一致。如： ①I think that he has done his best, hasn’t he? ②We think that English is very useful, isn’t it? （不用don’t we?） 八、反

23、意疑问句的陈述部分为I(We) don’t think(believe, suppose, consider)+ that从句时，从句为否定意义，问句部分的动词和主语仍与that从句保持一致且用肯定式。如： ①I don’t think that you can do it, can you? （不用do I?） ②We don’t believe that the news is true, is it? （不用do we?） 九、反意疑问句的陈述部分为非第一人称主语+ think(believe, suppose, consider) + that从句时，问句部分的动词和主语与

24、陈述部分的主句动词和主语保持一致。如： ①They all think that English is very important, don’t they? （不用isn’t it?） ②He didn’t think that the news was true, did he? （不用wasn’t/ was it?） 十、反意疑问句的陈述部分为主语+said( told, reported, asked……) + that从句时，问句部分的动词和主语与陈述部分的主句动词和主语保持一致。如： ①They said that you had finished your wor

25、k, didn’t they? （不用hadn’t you） ②Kate told you that she would go there, didn’t she? （不用wouldn’t she?） 十一、陈述部分的主语为不定代词something, anything, nothing, everything时，问句部分的主语用it。如： ①Something is wrong with the computer, isn’t it?②Nothing has happened to them, has it? 十二、陈述部分的主语为不定代词somebody(someone),

26、 anybody(anyone), nobody(no one), everybody(everyone)时，问句部分的主语用he或 they，这时问句动词的数应和he或 they一致。如： ①Someone has taken the seat, hasn’t he?②Everyone has done their best in the game, haven’t they? 十三、陈述部分为Let me……时，问句部分习惯上用shall I? 或will you?形式。如： Let me have a try, shall I?(will you?) 十四、陈述部分为Le

27、t us……时，问句部分习惯上用will you?形式。如： Let us stop to rest, will you? 十五、陈述部分为Let’s……时，问句部分习惯上用shall we?形式。如： Let’s go home together, shall we? 十六、陈述部分用上述情况以外的祈使句时，问句部分一般用will you?形式表示请求，用won’t you？形式表示委婉请求或邀请。如： ①Do sit down, won’t you?/ will you? ②You feed the bird today, will you? ③Please ope

28、n the window, will you?(won’t you?) 十七、陈述部分为否定祈使句时，问句部分一般用will you?形式。如： Don’t make any noise, will you? 十八、陈述部分为There (Here) + be + 主语时，问句部分用动词+there(here)?形式。如： ①There are two cakes on the plate, aren’t there? ②Here is a story about Mark Twain, isn’t here? 十九、陈述部分用had better +原形动词表示建议时，问

29、句部分用hadn’t +主语？形式。 ①You’d better tell him about the matter, hadn’t you?②We had better do it by ourselves, hadn’t we? 二十、陈述部分用used to +主语时，问句部分用didn’t + 主语？或usedn’t +主语？形式。 ①He used to live in the country, didn’t he?/usedn’t he? ②They used to be good friends, didn’t they?/usedn’t they? 二十一、

30、陈述部分用must(may, might) + have + V-ed表示推测时，若句中带有明显的过去时间的状语，问句部分动词用过去时形式。如： 整理为word格式 ①He might have forgotten his pen in the classroom yesterday, didn’t he? （不用mightn’t he?/ hasn’t he?） ②You must have got up late this morning, didn’t you?（不用mustn’t you?/haven’t you?） 二十二、陈述部分用must(may,

31、might) + have + V-ed表示推测时，若句中没有带明显的过去时间的状语，问句部分动词用现在完成时形式。如： ①Everyone must have known the death of the waitress, haven’t they? （不用mustn’t they?） ②You must have worked there a year ago, didn’t you?（不用mustn’t you?/ haven’t you?） 二十三、陈述部分的主语为从句时，问句部分的主语一般用it代替，如： ①What he said is true, isn\'t

32、it? （不用didn’t he?） ②Where we will build the dam has not been decided yet, has it? （不用won’t we?） 二十四、陈述部分的主语为动名词或不定式时，问句的主语用it代替。如： ①To do one good deed is easy for a person, isn\'t it?②Skating is your favorite sport, isn\'t it? 反意疑问句专题练习 1.I think they will go to town tomorrow, ________?

33、 A.do I B.don’t I C.will they D.won’t they 2.I don’t believe he can catch up with me, _________? A.can he B.can’t he C.do I D.don’t I 3.I’m sure that I will be well again, __________? A.am I B.aren’t I C.will I D.won’t I 4.I am afraid that he will not come, _______? A.am I B.aren’t I C.wil

34、l he D.won’t he 5.They don’t believe you are wrong, _________? A.are you B.aren’t you C.do they D.don’t they 6.He thought you were Beijing, _________? A.didn’t he B.did he C.weren’t you D.were you 7.We told you that he would come tonight, _______? A.didn’t we B.did we C.would he D.wouldn

35、’t he 8.The reporter said the news was not true, _________? A.wasn’t it B.didn’t he C.did he D.was it 9.They suggested that he should go to work at once, ________? A.did they B.didn’t they C.should he D.shouldn’t he 10.Your brother has lunch at home, _________-? A.hasn’t he B.doesn’t he

36、C.has he D.does he 11.John has to get up early, ________? A.has he B.hasn’t he C.does he D.doesn’t he 12.She has got to get everything ready, _________? A.hasn’t she B.has she C.doesn’t she D.does she 13.She has never been to China, _________?A.has she B.hasn’t she C.doesn’t she D.does she

37、 14.She had better tell you the news right now, _______? A.had she B.hadn’t she C.did she D.didn’t she 15.They would rather not have done that last week,________? A.would they B.wouldn’t they C.have they D.haven’t they 16.I’d rather stay here for a rest, ________?A.did I B.would I C.didn’t I

38、 D.wouldn’t I 17.You ought to do it again,_________?A.ought you B.oughtn’t you C.do you D.don’t you 18.You must do that again,_________?A.mustn’t you B.needn’t you C.do you D.don’t you 19.He must wait here, __________?A.mustn’t he B.doesn’t he C.shouldn’t he D.does he 20.He must be a good wo

39、rker,________?A.mustn’t he B.needn’t he C.isn’t he D.doesn’t he 21.He must have been to China twice,_________? A.hasn’t he B.didn’t he C.wasn’t he D.mustn’t he 22.He must have been ill last week,__________? A.hasn 整理为word格式 ’t he B.didn’t he C.wasn’t he D.mustn’t he 23.He must have k

40、nown you during the war,__________? A.hasn’t he B.didn’t he C.wasn’t he D.mustn’t he 24.He must have known the result already,_________? A.hasn’t he B.didn’t he C.wasn’t he D.mustn’t he 25.There used to be a temple here,________? A.didn’t there B.did there C.used there D.was there 26.The

41、y used to be good friends,________? A.usedn’t they B.didn’t they C.used they D.both A and B 27.Mother usedn’t to dress the baby,______? A.didn’t she B.did she C.used she D.usedn’t she 28.The students used to go to see him,_______? A.usedn’t they B.didn’t they C.used they D.both A and B 2

42、9.Alice, you have a little more chicken,________? A.haven’t you B.don’t you C.will you D.do you 30.Hi! Alice, you have bought a little chicken,_________? A.haven’t you B.won’t you C.will you D.have you 31.You two had breakfast just now,__________? A.hadn’t you B.didn’t you C.had you D.did

43、you 32.You two had finished the breakfast,_________? A.hadn’t you B.didn’t you C.did you D.had you 33.Neither you nor I was invited to the party,________? A.were we B.weren’t we C.was I D.were you 34.Either he or she is to clean the window,__________? A.are they B.aren’t they C.isn’t he

44、D.isn’t she 35.It is Jiao Yulu who turned Lankao into a rich district,_______? A.is it B.isn’t it C.did he D.didn’t he 36.It was you who never made such mistakes,________? A.wasn’t it B.weren’t you C.did you D.didn’t you 37.The little child dared not climb the tree,________? A.dared he B

45、.did he C.was he D.does he 38.What he said is not wrong,__________? A.didn’t he B.did he C.is it D.isn’t it 39.That his parents were ill made him a little worried,_________? A.weren’t they B.were they C.didn’t it D.wasn’t it 40.He dislikes what you have said,__________?A.does he B.doesn’t he

46、 C.have you D.haven’t you 41.(2003Shanghai spring)If you want help—money or anything,let me know,____you? A.don’t B.will C.shall D.do 42.(2002Shanghai)Mrs. Black doesn’t believe her son is able to design a digital cameral,____? A.is he B.isn’t he C.doesn’t she D.does she 43.(2002Shanghai s

47、pring)Brian told you that there wasn’t anyone in the room at that time,___? A.was there B.wasn’t there C.didn’t he D.did he 44.(2001Shanghai)I don’t suppose anyone will volunteer,_____? A.do I B.don’t I C.will they D.won’t they 45.(2000Shanghai)The news that they fialed their driving test di

48、scouraged him,___? A.did they B.didn’t they C.did it D.didn’t it 46.(NMET99)—Alice,you feed the bird today,____? --But I fed it yesterday. A.do you B.will you C.didn’t you D.don’t you 整理为word格式 虚拟语气 有些条件句是可能实现的,称为真实条件句. 虚拟语气是动词的一种特殊形式,用来表达说话人的意愿.请求,设想,等未能或不可能实现的事实,或说话人看来

49、实现可能性很小的情况.做这类题时首先要弄清楚虚拟语气的各种句型,即由if引导的虚拟条件句,省略if的倒装形式,可跟虚拟语气的宾语从句,同位语从句,表语从句的句型,以及表示祝愿或感叹的句子和由without, but for等介词引导的短语或句子. 高考对虚拟语气的测试主要涉及以下方面: 1). 主语从句,同位语从句中虚拟语气的用法. 2). 宾语从句中虚拟语气的用法,尤其是wish 虚拟语气结构的用法. 3). If条件句中虚拟语气的用法,应特别注意省略if的倒装结构是考试的重点. 4). would rather 等结构中虚拟语气的用法. 5). if only结构中

50、虚拟语气的用法. 6). But, or, otherwise 等含蓄条件句的用法. 7). It’s time (that) 等结构中虚拟语气的用法. 1. 虚拟语气在虚拟条件句中的运用 (1)虚拟语气现在时. 用以表示与现在事实相反的假设或现在实现可能性不大的情况. 条件从句 主句 动词过去式(be多用were) Would/should/could/might + 动词原形 Eg. If I were a bird, I would fly to you. If it were not for their

51、help, we should be in a very difficult position. (2) 虚拟语气过去式. 表示与过去事实完全相反的假设. 条件从句 主句 had + 过去分词 would/should/could/might + have +过去分词 Eg. If we had started earlier, we should not have missed the train. If she hadn’t been ill, she might have come. (3)虚拟语气将来式.

52、表与将来情形相反的假设或极少有可能实现的情况. 条件从句 主句 动词过去式或should +动词原形或were to +动词原形 would/should/could/might +动词原形 Eg. If Professor Li should have time tomorrow, we could ask him some questions. If there should be no air, there would be no living things. ◆ 书面语中,上述(1),(2),(3)三种时态的虚拟句中,如

53、果从句里含有should, had, were或其他助动词,则可将从属连词if省去,将助动词.情态动词.be或have放在句首形成部分倒装. Eg. Were he in your position, he’d have done the same. Had I had time, I would have done that yesterday. Should he come tomorrow, I should give him the dictionary. (1) 错综时间虚拟句 通常情况下,在非真实条件句中主句和从句的谓语动词所指时间是一致的, 但有时也可能指不同

54、的时间,这时要根据上下文的意思采用不同的谓语动词形式. P 116, 2 Eg. If I were you, I would have taken his advice. (从句指现在, 主句指过去) If I had taken my raincoat with me this morning, I would not be wet now. (从句指过去,主句指现在). (2) 含蓄条件句 有时假设的情况并不以条件从句表示出来,二是暗含在上下文中,比如通过介词短语来表示. Eg. But for your advice, I could not have done i

55、t so successfully. The change could not have taken place without the open-door policy. I was so busy then, Otherwise, I would have told him the answer. 3) 整理为word格式 虚拟语气在某些从句中的应用. A) 在wish, suggest, order, demand, propose, command, request, recommend, require, decide, insist, desire, ur

56、ge等动词的宾语从句以及would rather /sooner 后要用 “ (should) +动词原形” 来表示愿望,建议, 命令,要求等; 由上述动词派生或转化的名词suggestion, proposal, plan, motion, recommendation, demand, order, desire, request, requirement, insistence, advice, decision , obligatory 义不容辞的, 必须的 等的同位语从句或表语从句中也要用相应的虚拟形式. Eg. B) 在It is/was + 某些形容词 + that 从句

57、的句型中,that从句中的谓语动词常用虚拟语气,即 “should + 动词原形” 这些形容词有: important, necessary, essential, imperative, natural, strange, advisable, desirable, possible, probable, astonishing, surprising, desired, suggested, requested, recommended, ordered, proposed, decided, moved等. “ should + 动词原形(或完成形式)” 可表示惊奇,遗憾,怀

58、疑,不满等. ⅰ. 用于expect, believe, think, suspect 等动词的否定或疑问形式后的宾语从句中. Eg. I never expected that the new apartment should be so small. ⅱ. 用于 “It is a pity, it is a shame, it is no wonder 等 + that” 等结构后的主语从句中. Eg. It is a pity that he should be so careless. C) 在由for fear that, in case, lest 等引导的状语

59、从句中,用 “ should + 动词原形” 表示 “惟恐”的意思. Eg. He handled the instrument with care for fear that it should be damaged. D) 在 “ It is (about/ high ) time + that (从句)” 中,谓语动词常用过去式表表示虚拟语气. Eg. It is high time that people learnt English. E) 在 “as if/ as though” 引导的状语从句中,谓语动词与wish的宾语从句的虚拟形式相同. Eg. He wo

60、rks with such enthusiasm as if he never knew fatigue. He speaks English as though he were an American. F) 在 look, seem等动词后的 “as if / as though”从句中,当表示真实情况时,用陈述语气; 否则,用虚拟语气. Eg. It seems as if they know each other. (真实情况) It seems as though it were already spring. (虚拟语气) G) 用在if only 引起的感叹句

61、中. Eg. If only the driver didn’t drive so fast! 虚拟语气(Subjunctive Mood)这一语法项目是各类英语考试中心测试的重点之一。虚拟语气是一种特殊的动词形式，用来表示说话人所说的话并不是事实，而是一种假设、愿望、怀疑或推测。 Ⅰ用以表示虚拟条件的虚拟语气 ⒈ 用if条件从句表示的虚拟条件，是虚拟条件最普通的方式。 ① 虚拟现在时表示与现在事实相反的假设，其if 从句的谓语形式用动词的过去式(be 一般用were)，主句用would/ should/ could/ might +动词原形，例如：If I were i

62、n your position I would marry her. ② 虚拟过去时是表示与过去事实相反的假设，if 从句的谓语形式用过去完成时即had＋过去分词，主句用would / should / could / might + have +过去分词，例如：If it had not rained so hard yesterday we could have played tennis. ③ 大多数的虚拟条件句属于上面三种情况的一种，但并不排除存在条件和后果中，一个和现在情况相反，另一个和过去情况相反，例如：If you had followed what the doctor

63、 said, you would not have been so painful now.这个句子在高中出现频率颇高。 ④ 但是，如果后果用了虚拟语气，而条件却用陈述语气，这种用法是错的。 ⒉ 除了表示虚假条件外，if从句还可以表示对将来的推测，由于是将来还没有发生的，所以谈不上是真实的还是虚假的，只能说这个事情发生的可能性有多大。一般情况下，可以用陈述语气的if从句来表示对一个未来事实的推测，这个事实是完全可能发生的。If从句的谓语形式用一般过去式或用were to / should +动词原形，主句用would / should /could/ might +动词原形，例如：Je

64、an doesn't want to work right away because she thinks that if she were to get a job she probably wouldn't be able to see her friends very often.（1996年1月四级第44题） 整理为word格式 ⒊ 有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if 省去，而将had , should, were 等词提到主语之前，即用倒装结构,这时候，如果出现not等否定词，否定词需放在主语后面。这种结构在口语中很少使用，但频频出现

65、在各类考试中出现，例如：If it had not rained so hard yesterday we could have played tennis.→Had it not rained so hard yesterday, we could have played tennis. ⒋ 大多数的虚拟条件通过上面所讲的两种方法表达，但在个别句子中也可以通过介词without和介词短语but for表达，副词otherwise等表达出来。例如：We didn't know his telephone number; otherwise we would have telephoned

66、him.（1995年6月四级第46题）值得注意的是，包含but for的句子，谓语动词必定要用虚拟形式，但包含without等短语的句子，谓语动词未必一定要用虚拟语气。 ⒌ 有时虚拟条件不是明确地表达出来，而在蕴含在用but引导的从句里，于是便出现了有谓语动词是虚拟语气的主句加上谓语动词是陈述语气的but从句构成的并列复合句，例如I would have hung you but the telephone was out of order.在这样的句子里，如果主句没有用虚拟语气，或者从句用了虚拟语气，都是错的。 Ⅱ用在宾语从句中的虚拟语气 ⒈ 在表示愿望的动词wish后的宾语从句中，需用虚拟语气。（wish后的that 常省略），根据主句时态，从句谓语时态相应退后一位，例如：How she wished his family could go with him. ⒉ 在具有愿望、请求、建议、命令等主观意愿的动词(desire, demand, advice, insist, require, suggest, propose, order, recommend, de