whether和if的用法区别
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 come 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。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 whether 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
study studies am studying is studying are studying have studied
has studied have been studying has been studying
studied was studying were studying had studied had been studying
shall study will study shall be studying will be studying shall have studied
shall have been studying will have been studying
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“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：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 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／during 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］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
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, like, 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
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”，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。
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：
①Your father is unhappy, isn’t he?（不能用is he?）
②The 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?）
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 work, 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), 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Let 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 open 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、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：
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, 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 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, ________?
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.will 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’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
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
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 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 worker,________?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’t he
B.didn’t he
C.wasn’t he
D.mustn’t he
23.He must have known 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 https://www.360docs.net/doc/1d9272650.html,ed there D.was there
26.They used to be good friends,________?
https://www.360docs.net/doc/1d9272650.html,edn’t they
B.didn’t they
https://www.360docs.net/doc/1d9272650.html,ed they
D.both A and B
27.Mother usedn’t to dress the baby,______?
A.didn’t she
B.did she
https://www.360docs.net/doc/1d9272650.html,ed she
https://www.360docs.net/doc/1d9272650.html,edn’t she
28.The students used to go to see him,_______?
https://www.360docs.net/doc/1d9272650.html,edn’t they
B.didn’t they
https://www.360docs.net/doc/1d9272650.html,ed they
D.both A and B
29.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 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
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.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 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 spring)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 discouraged 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
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 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. 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 it 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) 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, urge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+ tha t” 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 + tha t (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 works 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 in 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 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：Jean 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）
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 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, decide …) 后的宾语从句中需用虚拟语气。谓语动词用(should) +动词原形。值得注意的是，如果宾语从句的动词是否定的，否定词not的位置应在动词之前，而不是动词之后。例如：The head nurse insisted that the patient not be move.另外，如suggest表达“暗示”，insist表示“坚持某种说法”时，后面的从句不用虚拟语气，例如：Her pale face suggests that she is ill.或He insisted that he did not kill the boy.
除此之外，上述动词也要求用虚拟式
①在It is+上述动词的过去分词，其后所跟的主语从句中，如It is suggested that pupils wear school uniforms.
②在上述动词相应的名词形式作主语+连系动词，其后的表语从句中，例如His suggestion was that classed be re-scheduled.
③在对上述动词相应的名词进行解释的同位语从句中，如：The workers raised the demand that their pay be increased to cope with the inflation.
⒊would （had）rather , would sooner也用来表达主观愿望，它们之后的宾语从句中需用虚拟语气。谓语动词用过去式表示现在或将来，用过去完成式表示与过去事实相反，例如：I would rather he went right now.
Ⅲ其他形式的虚拟语气
⒈it is +necessary等形容词后，that主语从句中虚拟形式使用，这类形容词包括necessary, important, essential, imperative, urgent, preferable, vital, advisable等，例如It is necessary that you listen to the teacher carefully.或者It is essential that you be able to pronounce every single word correctly.
⒉在It's (high/about) time 之后的定语从句中需用虚拟语气。谓语动词用过去式，例如It is high time that you went to school
⒊虚拟语气在as if / as though 引导的方式状语从句中的应用（谓语动词形式与wish后的宾语从句基本相同）表示与现在事实相反或对现在情况有怀疑，谓语动词用过去式。例如：He felt as if he alone were responsible for what had happened. 表示过去想象中的动作或情况，谓语动词用过去完成式。
⒋在lest 引导的状语从句中，谓语动词多用虚拟语气，(should )+ 动词原形。例如：The mad man was put in the soft-padded cell lest he injure himself.（1998年1月四级第38题）
⒌在if only 引起的感叹句中需用虚拟语气。谓语动词用过去式或过去完成式。例如：Look at the terrible situation I am in! if only I had followed your advice
虚拟语气
第一部分：语气的定义和种类
1 语气(mood)
语气是动词的一种形式，表示说话人对某一行为或事情的看法和态度。
2 语气的种类
⑴、陈述语气：表示动作或状态是现实的、确定的或符合事实的，用于陈述句、疑问句和某些感叹句。如：
①There are two sides to every question.每个问题都有两个方面。
②Were you busy all day yesterday?昨天一整天你都很忙吗？
③How good a teacher she is!她是多好的一位老师啊！
⑵、祈使语气：表示说话人对对方的请求或命令。如：
①Never be late again!再也不要迟到了。
②Don’t forget to turn off the light.别忘了关灯。
⑶、虚拟语气：表示动作或状态不是客观存在的事实，而是说话人的主观愿望、假设或推测等。如：
①If I were a bird, I could fly in the air.如果我是一只小鸟，我就能在空中飞行。
②I wish I could pass the examination.我希望我能通过考试。
③May you succeed!祝您成功！
虚拟语气在语法里算得上是个难点。让我们就从最简单的开始吧。
第二部分：简单句中的虚拟语气
一、情态动词的过去式用于现在时态时，表示说话人的谦虚、客气、有礼貌、或委婉的语气，常用于日常会话中。如：
⑴.Would you be kind enough to show me the way to the post office?请你告诉我去邮局的路好吗？
⑵.It would be better for you not to stay up too late.你最好别熬夜到很晚。
二、表祝愿。
1、常用“may+动词原形”表示祝愿，但愿，此时may须置于句首（多用于正式文体中）。
⑴、May good luck be yours!祝你好运！
⑵、May you be happy!祝你快乐！
⑶、May you do even better!祝你取得更大成就！
⑷、May you have a good time. 祝愿你玩的痛快。
⑸、May the friendship between us last long. 祝愿我们的友情天长地久。
⑹、May you be happy. (注意那个be ) 祝你幸福。
2、用动词原形。例如：
(1).Long live the people! 人民万岁！
(2).“God bless you,”said the priest.牧师说：“愿上帝保佑你！”
(3).Have a good journey! 祝愿你旅途愉快！
三、表示强烈愿望。（该类型虚拟语气谓语仅用动词原形，第三人称单数也不加“s”）
(1).God save me．(2).Heaven help us．
四、表命令
1.命令虚拟语气只能用在第二人称(you)，而且通常省略主语(也就是you)。
2.句子尾通常加上感叹号：！
3.虚拟语气动词用一般现在时态(Simple Present)，如：work, be , go
4.否定形式的命令语气，可用助动词do，加上not。
(1). Work ! (2). Work harder ! (3). Be more alert ! (虚拟语气动词Be) (4). You go out !
(5). Do not work so hard. (do not 表示否定的虚拟语气)
(6). Don't be afraid. (口语中常用don't 代替do not)
五、在一些习惯表达中。如：
(1).You’d better set off now.你最好现在就出发。
(2).I’d rather not tell you the secret.我情愿不告诉你这个秘密。
虚拟语气虚拟语气表示说话人的主观愿望、猜测、建议或与事实不符的假设等，也可以表示可能性较小的情况或不可能发生的情况，而不是客观存在的事实（表示客观事实要用陈述语气）。虚拟语气是由句中谓语动词的特殊形式表现出来的。虚拟语气常用于复合句中，也可用于简单句。
一、虚拟语气的用法
I. Present Unreal:
If I (you, he / she, we, they) + 动词过去式(were, did, had, etc.), should / would / could / might + 动词原形
e.g. If I had HIV, I would know because I would fell sick.
If I were you, I would give an AIDS patient a hug.
II. Past Unreal:
If I (you, he / she, we, they) + had + 过去分词, should / would / could / might + have + 过去分词
e.g. If she had told him about the danger, he would not have got hurt.
If I had known more about giving first aid, I could have helped them.
III. Future impossible:
1. If I (you, he / she, we, they) + 动词过去式(were, did, had, etc.), … should / would / could / might + 动词原形
e.g. If the teacher asked me to solve the problem next time, I could try my best.
2. If I (you, he / she, we, they) should +动词原形, … should / would / could / might + 动词原形
e.g. If he should fail in the experiment this time, he would try again.
3. If I (you, he / she, we, they) + were to +动词原形, should / would / could / might +动词原形
e.g. If we were to panic, we would not be able to help.
二、虚拟语气应该注意的问题
I. 关于假使条件虚拟语气需注意的几点
1. 如果从句所假设的谓语动词发生的时间与主句所假设的谓语动词发生的时间不一致, 这种假设条件句叫错综时间条件虚拟语气. 其主句和从句谓语动词的构成要根据所假设的时间而定.
1) If I had taken the medicine, I would be better now. 如果我服用了那种药的话, 现在就会好些了.
2) If the weather had been finer, the crops would be growing still better. 如果(前些日子)天气更好些, 庄稼一定会长得更好.
2. If it were not for / had not been for… 也是一种条件虚拟语气从句, 译为“要不是因为……”.
1) If it hadn’t been for the doctor, he wouldn’t have recovered so soon.
2) If it were not for the lack of space, we would hold the sports meet today.
3. 有些条件是由一些短语引出的(but for, with, without; otherwise, or, but, etc,)
1) We couldn’t have achieved so much without your help (= If we had not had your help).
2) Without solar radiation, animals and plants would die.
3) With better equipment, we could have done it better.
4) But for electricity (= If there were no electricity), there would be no modern industry.
5) I should have returned the book last week, but I was so busy that I forgot to do so.
6) He was having a meeting; otherwise he would have come over to help us.
7) He felt very tired yesterday, or he would have attended the party.
4. 在某些隐含的虚拟条件简单句中, 虚拟语气可通过上下文表现出来. 谓语动词用虚拟形式.
1) Any men in his position would have done like that.
2) You should (ought to) have come earlier.
II. 虚拟语气祈使语气的混合使用
在有些情况下, 条件从句中的谓语由”should + 原形动词” 构成, 这时主句的谓语动词既可以是虚拟语气或陈述语气, 也可以是祈使语气.
1. If it should rain, the plan will / would be called off.
2. Should anyone phone, please tell them I’m busy.
3. Even if (If) it should get stormy, I will go.
III. 表示要求, 建议, 命令的虚拟语气
表示要求, 建议, 命令的从句中, 谓语动词要用should + 原形动词, 其中可以should 省略. 下列例句可以表示这种虚拟语气.
a. 主宾语从句表示法: suggest, order, request, advise, require, insist, ask, demand, command, propose等动词后面的宾语从句要用原形动词should + 原形动词, 可以省略.
1. The doctor advised that I (should) take a rest.
2. The London dockers demanded that their wages (should) be raised.
3. He insisted that the meeting (should) not be put off.
当suggest, insist 等动词表示”暗示, 坚持说” 时, 其宾语从句中的谓语动词不需要用虚拟语气, 要用陈述语气.
1. Are you suggesting that I am not suited for the job?
2. He insisted that he was innocent.
b. 主语从句表示法: 当以上动词用在下列句型中时, 主语从句也应该用should + 原形动词
1. It is suggested that the building (should) be pulled down.
2. It is ordered that the work (should) be started at once.
在It is (was) strange (necessary, wonderful, important, etc.) that…句型中, strange, necessary等后面的主语从句中用should + 原形动词, should可以省略.
3. It is strange that he (should) refuse to come to the party.
4. It is necessary that a doctor (should) be sent for at once.
5. It is important that we should learn from toehrs.
e. 表语从句表示法.
suggestion, proposal, order, advice, demand 等名词作主语时, 其后面的表语从句中也用虚拟语气, 即should + 原形动词, should 也可以省略.
1) My advice is that you (should) give up smoking.
c. wish 后面所跟宾语从句要求谓语动词用虚拟语气.
e.g. I wish that she were here with me and that we weren’t sick.
I wish I had sent the old man to hospital in time.
d. 在as if引起的从句中,动词一般用虚拟语气, 通常用were
e.g. People treat me as if I were a dangerous person.
I remember the whole thing as if it happened yesterday.
f. 同位语从句表示法.
1. That evening came the order that we (should) cross the river at once.
IV. 虚拟语气中常见的句型有
1. It is (high / about) time that… 这一从句的谓语动词用过去式或should + 原形动词, 其中should不可以省略. 此句型译为”该是……时候了”.
2. would rather sb. did sth. / had done sth.
此句型表示”宁愿让某人……”, 如果是没有发生的动作, 从句用过去时; 如果是已经发生的事, 从句用过去完成时.
1) I’d rather you left tomorrow.
2) I’d rather they hadn’t gone to school yesterday.
3. if only…
此句型表示”要是……就好了”. 其后面句子的时态与wish引导的宾语从句相同, 既:如果虚拟现在, 要用一般过去时; 如果是虚拟过去, 要用过去完成时; 如果是虚拟将来, 则应该用would或could加原形动词.
1) If only I were a bird!
2) If only I had worked hard as a student!
3) If only I could land on the moon!
4. 连接词in case可用来引起的虚拟语气. 形式通常为: in case + 主语+ should +动词原形. in case句中should 的可以省去, 也可以不用虚拟语气, 而用陈述语气.
1) He took his rain coat with him in case it should rain.
2) He doesn’t dare to leave the house in case he is (should be) recognized.
虚拟语气单项选择:
1. If I had had enough time, I my work.
A. would finish
B. must have finished
C. would have finished
D. had finished
2. Ten minutes earlier, they the plane.
A. will catch
B. would catch
C. would have caught
D. will have caught
3. Mr. Green requires that the students a composition every other week.
A. write
B. written
C. would write
D. will write
4. Had he studied hard, he the exam.
A. would pass
B. could pass
C. had passed
D. would have passed
5. I wish I what is happening there in his room.
A. know
B. known
C. knew
D. should know
6. It is important that you sports every day.
A. have
B. would have
C. must have
D. will have
7. If there were no water in the world, everything .
A. will die
B. would die
C. would have died
D. would have been dead
8. what was going to happen ,I would never have left her alone.
A. Had I known
B. If I know
C. If I knew
D. If had I known
9. He ordered that the work right away.
A. should finish
B. finished
C. would be finished
D. be finished
10. — Shall we go to the movie tonight?
— No, I'd rather at home with our baby. You'd better not leave it to the babysitter at night.
A. you stayed
B. you stay
C. stayed
D. stay
11 .in your position, I would help him.
A. Was I
B. Were I
C. If I am
D. If I had been
12. I , but I was stopped by the heavy rain.
A. mean to come
B. meant to come
C. had meant to come
D. meant coming
13. Mrs. Black insists in that old hotel.
A. not to stay
B. not staying
C. staying not
D. that he not stay
14. If you had spoken clearly, you would .
A. understand it
B. have understood
C. be understood
D. have been understood
15. If you that late movie last night, you wouldn't be so sleepy.
A. haven't watched
B. hadn't watched
C. didn't watch
D. wouldn't have watched
16.The foreign friend speaks Chinese so well as if he a Chinese.
A. is
B. be
C. should be
D. were
17. — If he , he that food.
— Luckily he was sent to the hospital immediately.
A. was warned; would not take
B. would be warned; had not taken
C. had been warned; would not have taken
D. would have been warned; had not taken
18. Without electronic computers, much of today's advanced technology _______ achieved.
A. will not be
巧记whether与if异同讲课稿
巧记w h e t h e r与i f 异同
巧记whether与if异同 主从表从同位从，if不用whether用； discuss和介词后，whether引宾从； 不定式、or not后在跟，whether独能显神通； 宾从若是否定句，if发挥其功用； 避免歧义要慎重，其他情况可换用。 一、引导主语从句，常用whether． (1)Whether the meeting will be held is uncertain．会议是否召开还不能确定． (2)It is unknown whether he will come．他是否来还不知道。 3.Whether we’ll go camping depends on the weather. 二、引导表语从句常用whether (1).The question is whether he can finish the work by the end of this week． 问题是到这周末他是否能完成这个工作。 (2).What we want to know is whether he will come to speak to us． 我们想知道的是他能否来给我们讲话。 3.The question is whether it is worth doing. 三、引导同位语从句，常用whether. (1).The question whether he will come is important．他是否来这个问题很重要。 (2).The plan whether we’ll go outing tomorrow hasn’t been made．明天我们是否郊游这个计划还没订。 (3).The question whether we need it has not been decided. 四、引导宾语从句。引导及物动词的宾语从句，用whether, if皆可； 介词的宾语从句，一般只用whether引导；
九年级中考复习：whether和if区别【含答案】
whether 和if区别 whether和if都可以引导宾语从句，表示“是否”，在口语或间接引语中两者可以互换使用。如： I wonder if / whether I can get some advice from you. Ask him whether / if he can come. 但在有些情况下，whether和if的用法有一定区别。 1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如： 正： Let me know whether you can come or not. 误： Let me know if you can come or not. 2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如： 正：Whether it is true or not, I can’t tell. 误：If it is true or not, I can’t tell. 3. whether可以引导带to的不定式，if则不能。如： 正：I don’t know whether to accept or refuse. 误：I don’t know if to accept or refuse. 4. whether及其引导的成分可放于介词之后，作介词的宾语，但if不能。如： 正： I worry about whether I hurt her feelings. 误： I worry about if I hurt her feelings. 5. whether可以引导从句，作主语、表语或同位语，而if不能。如： 正： It was uncertain whether he would come. 误： It was uncertain if he would come. 正： His first question was whether Tom had arrived yet. 误： His first question was if Tom had arrived yet. 正： We must consider the question whether we will take these measures. 误： We must consider the question if we will take these measures. 强化练习： 1. The question has not been answered ____ Taiwan will be included on the Olympic
whether和if的用法区别
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。 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. 和if都可用it作形式主语从句中。如：it's uncertain whether/if he'll come 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。 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. 答案是C。 可用在介词之后，引导宾语从句，而If则不能。如：Success depends on whether we make evough effort. 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. 后可接不定式，而if不能。如：Please tell us whether 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 study studies am studying is studying are studying have studied has studied have been studying has been studying studied was studying were studying had studied had been studying shall study will study shall be studying will be studying shall have studied shall have been studying will have been studying 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“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：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
If和+whether的用法讲课教案
If和whether if不能替换whether的5种情况 1.正式文体中，句中有or not 时 2.引起主语，表语，同位语从句时 3.作介词宾语时 4.放不定式前，与不定式组成词组时 5.作discuss等词的宾语时 以上是if和whether表示"是否"之意的区别，此外，if还有加入的意思，引起条件状语从句；而whether 另有不管无论之意，引起让步状语从句 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 come 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。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 worthdoing. 4.在名词之后引导同位语从句时，用whether而不用if。如：The puestion 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 whether 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. whether和if都可以引导宾语从句，表示“是否”，在口语或间接引语中两者可以互换使用。如： I wonder if / whether I can get some advice from you. Ask him whether / if he can come. 但在有些情况下，whether和if的用法有一定区别。 1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如： 正：Let me know whether you can come or not. 误：Let me know if you can come or not. 2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如： 正：Whether it is true or not, I can’t tell. 误：If it is true or not, I can’t tell. 3. whether可以引导带to的不定式，if则不能。如： 正：I don’t know whether to accept or refuse.
if与whether用法区别
if与whether用法区别 收集整理：王俊尧 1.下列情况只能用whether： （1）直接与or not连用时,往往用whether(if…or not也可以使用)。如: Let me know whether or not he will come. (= Let me know whether / if he will come or not.) 让我知道他是否能来。 I don't know whether or not he does any washing. (= I don't know whether / if he does any washing or not.) 我不知道他在家洗不洗衣服。 I wonder whether we stay or whether we go. 我想知道我们是去还是留。 (2) 在介词之后用whether。如： I'm interested in whether he likes English． 我关心的是他是否喜欢英语。 We're thinking about whether we can finish the work on time． 我们正在考虑是否能按时完成这项工作。 I worry about whether I hurt her feelings． 我担心是否伤了她的感情。 (３)在不定式前用whether。如： He hasn't decided whether to visit the old man． 他尚未决定是否拜访那位老人。 I don't know whether to go．我不知去否。 He hasn't decided whether to go by bus or by train． 他还未决定是乘公共汽车去还是坐火车去。 （４）whether置于句首时，不能换用if。如： Whether this is true or not，I can't say． 这是否真的我说不上来。 （５）引导主语从句和表语从句时宜用whether。如： Whether she will come or not is still a question． 她是否能来还是个问题。 The question is whether we can catch the bus． 问题是我们能否赶上公共汽车。 （６）若用if会引起歧义时，则用whether。如：
whether和if用法
1.whether和if均可用来引导主语从句，但if引导的从句不能位于句首。 如：Whether they win or lose is all the same to me. 他们是赢是输於我都一样.（此时whether不能换作if ） It's doubtful whether there'll be any seats left.说不上还有没有空座位了.(此句whether能换作if) 2.whether和if均可用来引导宾语从句。如： ①I don't know whether/if I will be able to come.我不知道我是否能来. ②She asked me whether/if I was interested in working for her.她问我是否有兴趣为她工作。 ③We'll be told tomorrow whether we should take the exam or not.我们明天才知道是不是应该参加考试. ④I asked him whether he had done all the work himself or whether he had had any assistance. 我问他这些工作都是他自己做的还是别人帮他做的. ( 注意: 在两个供选择的从句之间若用or字, 则须重复whether一字. ) 注:⑴当强调宾语从句并将其提前时只能用whether。 如:Whether I'll have time to go with you I am not sure.我很难说我们是否有时间跟你们一起去。 ⑵从句作介词宾语时只用whether不用if。 如:She was undecided about whether she should accept his offer. 她拿不定主意应该不应该接受他的好意 ⑶当whether和or not连用时，只用whether不用if。当or not放在whether引导的从句句尾，则可以用if来替换。 如: I don’t know whether or not he will come.我不知道他是不是回来。 I'll be happy whether/if I get the job or not我能不能得到那份工作都一样高兴 ⑷当whether和or 连用表示明确的选择时，只用whether不用if。 如:He asked me whether I wanted to go there by train or by bus. 他问我是想乘火车还是坐公共汽车去那里。 He hesitated about whether he should drive or take the train.他开车去还是坐火车去, 犹豫不决注:whether 和or 连用还可以引导让步状语从句,此时也不用if。 如：We'll go on with the work, whether we can find the necessary tools or not. 不管我们能否找到所需的工具,我们要把这件工作做下去。 Whether or not it rains / Whether it rains or not, we're playing football on Saturday. 无论下不下雨, 我们星期六一定踢足球. ⑸动词discuss，decide,consider等后习惯上也常用Whether引导从句，不用if。 They discussed whether they should leave at once.他们讨论了是否应该马上离开。We discussed whether the house should be sold. 我们讨论了这房子是否应卖掉。 3.表语从句用whether引导不用if. 如:①The doubt was whether you had broken the beautiful vase. 疑问是你是否打坏了这只漂亮的花瓶。 4.同位语从句用whether引导不用if. 如:①The question whether we'll build another lecture building hasn't been settled. 是否要另建一幢教学楼的问题还未决定。 5. 在动词不定式之前，只能用whether，不能用if。 如:①The question is whether to go to Munich or Vienna. 问题是去慕尼黑还是去维也纳. ②She doesn't knows whether to get married now or wait. 是否现在结婚或是等待她不知道。 ③We were wondering whether to go today or tomorrow. 我们弄不清是今天走还是明天走. ④I'm not sure whether to resign or stay on. 我拿不准主意是辞职还是留任. Answers: BADDC ABCAB ABADD B
If 和whether的区别 (含 讲解+习题+答案)教学文稿
If 和whether的区别 if和whether都可译为\"是否\",二者引导宾语从句时通常可以互相替换,口语中多用if 代替whether.例如：Ask if/whether he plans to come to the meeting. 而以下几种情况中, 只能用whether: 1. 强调两方面的选择,特别是句中有or not时.如： Let me know whether you can come or not. 2. 宾语从句前置时.如： Whether this is true, I can\'t say. 3. 引导主语、表语、同位语从句时.如： Whether the football game will be played depends on the weather. （主语从句） The question is whether he can do it. （表语从句） The question whether we should go with them must be decided at once. （同位语从句） 4. 在介词之后作介词的宾语时.如： I haven\'t settled the question of whether I\'ll go back home. 5. 在不定式前与不定式一起组成词组时.如： Whether to go or stay is still a question. 6. 在discuss, decide 等动词后作宾语时.如： We discussed whether we should go there by plane. 值得注意的是：if还可以引导条件状语从句,是\"假如；如果\"之意,而whether可以引导让步状语从句,是\"不管；无论\" 之意.如： If you ask him, he will help you. I shall go, whether you come with me or stay at home. 一、if或whether引导宾语从句时,作“是否”讲,常放在动词ask 、see 、say 、know 和find out等后面.一般情况下,两者常可换用,在口语中多用if.如： 例1 Nobody knows whether (if) it will rain tomorrow. 没有人知道明天是否下雨. 例2 Lucy asked whether (if) they had a cotton sweater .露西问他们是否有棉制的羊毛衣. 二、if或whether引导宾语从句时,要注意三个方面,即连词、语序和时态. 1 if或whether不能和that 或其它连词（副词）同时使用,也不能省去.如： 例3 我不知道他今天是否会来. [误] I don’t know that if(whether) he will come here today . [正] I don’t know if(whether) he will come here today . 例4他走过来看看猫是否出了毛病. 误] He came to see what if (whether) there was wrong with his cat . [正] He came to see if (whether) there was wrong with his cat . 2 if或whether引导的宾语从句时,虽具有疑问意义,但从句语序应用陈述句语序.如：例5 Did you know the way to the hospital ? The old woman asked me . The old woman asked me .if (whether) I knew the way to the hospital .老妇人问我是否知道去医院的路. 3 if或whether引导的宾语从句应和主句的时态保持一致.即主句为一般现在时,从句用
If和whether的区别含讲解+习题+答案.docx
I f和w h e t h e r的区别 if 和 whether都可译为\"是否\",二者引导宾语从句时通常可以互相替换代替 whether.例如：Ask if/whether he plans to come to the meeting. 几种情况中 , 只能用 whether:,口语中多用 if 而以下 1.强调两方面的选择 ,特别是句中有 or not 时.如： 2.宾语从句前置时 .如： 3.引导主语、表语、同位语从句时 .如： Whether the football game will be played depends on the weather.（主语从句） The question is whether he can do it.（表语从句） The question whether we should go with them must be decided at once.（同位语从句） 4.在介词之后作介词的宾语时 .如： 5.在不定式前与不定式一起组成词组时 . 如： Whether to go or stay is still a question. 6. 在 discuss, decide等动词后作宾语时 .如： We discussed whether we should go there by plane. 值得注意的是：if 还可以引导条件状语从句 ,是\" 假如；如果 \" 之意 ,而 whether 可以 引导让步状语从句 ,是 \" 不管；无论 \" 之意 .如： If you ask him, he will help you. I shall go, whether you come with me or stay at home. 一、if 或 whether引导宾语从句时 ,作“是否”讲 , 常放在动词 ask 、see 、say 、know 和 find out 等后面 . 一般情况下 ,两者常可换用 , 在口语中多用 if. 如： 例 1 Nobody knows whether (if) it will rain tomorrow.没有人知道明天是否下雨. 例 2 Lucy asked whether (if) they had a cotton sweater .露西问他们是否有棉制的羊毛衣 . 二、 if 或 whether引导宾语从句时 ,要注意三个方面 ,即连词、语序和时态 . 1 if或 whether不能和 that 或其它连词（副词）同时使用,也不能省去 . 如： 例 3我不知道他今天是否会来 . [ 误 ] I don ’ t know that if(whether) he will come here today . [ 正 ] I don ’ t know if(whether) he will come here today . 例 4他走过来看看猫是否出了毛病 . 误] He came to see what if (whether) there was wrong with his cat . [ 正 ] He came to see if (whether) there was wrong with his cat . 2 if 或 whether引导的宾语从句时,虽具有疑问意义,但从句语序应用陈述句语序. 如：例5 Did you know the way to the hospital ? The old woman asked me . The old woman asked me .if (whether) I knew the way to the hospital .老妇人问我是否知道去医院的路. 3 if 或 whether引导的宾语从句应和主句的时态保持一致. 即主句为一般现在时,从句用
if和whether的用法
if和whether的用法： 一、if或whether引导宾语从句时，作“是否”讲，常放在动词ask 、see 、say 、know和find out等后面。直接引语如果为一般疑问句，变为间接引语时就用if或whether引导，并把疑问句语序变为陈述句语序。一般情况下，两者常可换用，在口语中多用if。如： 二、if或whether引导宾语从句时，要注意三个方面，即连词、语序和时态。 ◆if或whether不能和that 或其它连词（副词）同时使用，也不能省去。 ◆if或whether引导的宾语从句时，虽具有疑问意义，但从句语序应用陈述句语序。 ◆if或whether引导的宾语从句应和主句的时态保持一致。即主句为一般现在时，从句用任一种时态；主句为一般过去时，从句则用过去时中的任一种时态。 ◆如果主句中的时态为一般过去时，从句中的时态要求发生相应的变化与主句的时态保持一致。（表示客观规律，自然现象和真理的则不变。） 三、if和whether的区别： ◆在动词不定式之前只能用whether 。 ◆在whether ……or not 的固定搭配中。 ◆在介词后，只能用whether。 ◆宾语从句放在句首表示强调时，只能用whether 。
◆用if会引起歧义时，只用whether。如用whether可避免歧义 eg：“Are they from France?”He asked me . →He asked me if they were from France. My physics told us that light travels faster than sound. 物理老师告诉我们光比声音传播的快。
if 和 whether 用法区别
if 和 whether 用法区别 1. 引导宾语从句 在引导宾语从句时，whether和if通可以互换，在 ask,care,doubt,know,learn,see,tell,try,wonder等动词之后尤其如此。例They don’t care a bit whether my reports are good or bad.. I am not sure if/whether I’ll have time. 但是，必须注意以下几点： 1）如果从句是否定结构，则用if不用whether.例如： I don’t care if he doesn’t show up .他来不来我都不在乎。 但是，当doubt是否定式时，则不用whether或if，要改用that,因为句子本身已没有“怀疑”或选择之意。度比较： She never doubt for a moment that she was right.她对自己是正确的这一点从不怀疑。 I doubt if that was what he wanted. 2)宾语从句前置时只能用whether,如： Whether he lives there,I want to know. 3）在decide,dicuss等动词后，通常只跟whether引导的宾语从句。如： They dicussed whether they should close the shop. 4)出现在介词后面的宾语从句只能用whether引导，如： It all depends on whether she likes the boss or not .一切都取决于她是否喜欢这位上司。 5）句中含有引导条件状语从句的if时，用whether不用if，如： Bill asked whether ,if I got the job,I’d move to York.比尔问如果我得到这份工作是否还要迁到约克。 2．引导主语从句 主语从句位于句首时，用whether不用if Whether they win or lose is all the same to me. Whether it will do us harm or good remains to be seen. 但是，当采用形式主语it,而将主语从句后置时，用whether和if均可（尽管whether更常用）： It makes no difference to me whether/if it’s foggy or clear..(高二册，第220页) 3．引导表语从句 引导表语从句时，一般用whether.例如： The question is whether they can cooperate with us.问题是他们能否与我们合作。 4．引导同位语从句时一般用whether.例如： We will soon discuss the problem whether we should take some effective measures to protect the animals and plants in our region.我们很快将讨论是否应该采取一些有效措施来保护本地区的动植物这一问题。 5．引导让步状语从句 1)引导让步状语，一般用whether.例如： Whether you like it or not ,you’ll have to do it . Whether the weather is good or bad ,they will set off as they planned.无论天气是好是坏，他们都将按计划启程。
If和whether的区别(含讲解+习题+答案)(可编辑修改word版)
If 和whether 的区别 if 和whether 都可译为\"是否\",二者引导宾语从句时通常可以互相替换,口语中多用if 代替whether.例如：Ask if/whether he plans to come to the meeting. 而以下几种情况中, 只能用whether: 1.强调两方面的选择,特别是句中有or not 时.如： Let me know whether you can come or not. 2.宾语从句前置时.如： Whether this is true, I can\'t say. 3.引导主语、表语、同位语从句时.如： Whether the football game will be played depends on the weather. （主语 从句） The question is whether he can do it. （表语从句） The question whether we should go with them must be decided at once. （同位语从句） 4.在介词之后作介词的宾语时.如： I haven\'t settled the question of whether I\'ll go back home. 5.在不定式前与不定式一起组成词组时.如： Whether to go or stay is still a question. 6.在discuss, decide 等动词后作宾语时.如： We discussed whether we should go there by plane. 值得注意的是：if 还可以引导条件状语从句,是\"假如；如果\"之意,而whether 可以引导让步状语从句,是\"不管；无论\" 之意.如： If you ask him, he will help you. I shall go, whether you come with me or stay at home. 一、if 或whether 引导宾语从句时,作“是否”讲,常放在动词ask 、see 、say 、know 和find out 等后面.一般情况下,两者常可换用,在口语中多用if.如： 例1 Nobody knows whether (if) it will rain tomorrow. 没有人知道明天是否下雨. 例2 Lucy asked whether (if) they had a cotton sweater .露西问他们是否有棉制的羊毛衣. 二、if 或whether 引导宾语从句时,要注意三个方面,即连词、语序和时态. 1if 或whether 不能和that 或其它连词（副词）同时使用,也不能省去.如： 例3 我不知道他今天是否会来. [误] I don’t know that if(whether) he will come here today . [正] I don’t know if(whether) he will come here today . 例4 他走过来看看猫是否出了毛病. 误] He came to see what if (whether) there was wrong with his cat . [正] He came to see if (whether) there was wrong with his cat . 2if 或whether 引导的宾语从句时,虽具有疑问意义,但从句语序应用陈述句语序.如： 例5 Did you know the way to the hospital ? The old woman asked me . The old woman asked me .if (whether) I knew the way to the hospital . 老妇人问我是否知道去医院的路.
if与whether的区别
1、引导宾语从句 在引导宾语从句时，whether 和if 通可以互换，在ask,care,doub,know,learn,msee,tell,try,wonder等动词之后尤其如此。例如： I don’t know if/whether I can help you. They don’t care a bit whether my reports are good or bad.. I wonder if you can examine him now.(高一册第十四页) I am not sure if/whether I’ll have time. 但是，必须注意以下几点： 1）如果从句是否定结构，则用if不用whether.例如： Well,think,and see if the most religious people aren’t those who fell that this life doesn’t gice them all they want.好，你想，那最虔诚的宗教徒，是不是就是那此觉得这现实的人生没有完全满足自己欲望的人？ Dinner was almost over when Dan,still looking hungry,grinned and asked Dave if he wasn’t going to have some bread.晚饭快吃完的时候丹（他看上去还没吃饱）笑着问戴维还要不要吃些面包。 I don’t care if he doesn’t show up .他来不来我都不在乎。 Let me know if you can’t meet me at Jackson and Throop Streets Wednesday afternoon at two o’clock.星期三下午奉告警方，你是否能在杰逊街和思鲁街的黑心角来跟我相会。（＜嘉莉妹妹＞＝ 当然，对某些句子，人们可能会有不同的理解。如上面最后两列中的if 也可理解为引导条件状语从句： 他不来我也不在乎。 如果你在星期三下午二时不能和我在杰克逊街和思鲁街的黑心角相会，请通知我。 但是，当doubt是还定式时，则不用whether或if，要改用that,因为句子本身已没有“怀疑”或选择之意。度比较： I don’t doubt that you are honest.我不怀疑你的诚实。 She never doubt for a moment that she was right.她对自己是正确的这一点从不怀疑。 I doubt whether it’s true. I doubt if that was what he wanted. 2)宾语从句前置时只能用whether,如： Whether he lives there,I want to know.
whether 和if 的用法
初三 Whether 和if 的用法 1.whether 和if 均可用来引导主语从句，但if 引导的从句不能位于句首。 如： Whether they win or lose is all the same to me. 他们是赢是输於我都一样.（此时whether 不能换作if ） It's doubtful whether there'll be any seats left. 说不上还有没有空座位了. (此句whether 能换作if) 2.whether 和if 均可用来引导宾语从句。 如：①I don't know whether/if I will be able to come.我不知道我是否能来. ②She asked me whether/if I was interested in working for her.她问我是否有兴趣为她工作。 ③We'll be told tomorrow whether we should take the exam or not.我们明天才知道是不是应该参加考试. ④I asked him whether he had done all the work himself or whether he had had any assistance. 我问他这些工作都是他自己做的还是别人帮他做的. ( 注意: 在两个供选择的从句之间若用or 字, 则须重复whether 一字. ) 注: ⑴当强调宾语从句并将其提前时只能用whether 。 如:Whether I'll have time to go with you I am not sure.我很难说我们是否有时间跟你们一起去。 ⑵ 从句作介词宾语时只用whether 不用if 。 如:She was undecided about whether she should accept his offer.她拿不定主意应该不应该接受他的好意 ⑶ 当whether 和or not 连用时，只用whether 不用if 。当or not 放在whether 引导的从句句尾，则可以 用if 来替换。 如: I don’t know whether or not he will come.我不知道他是不是回来。 I'll be happy whether/if I get the job or not 我能不能得到那份工作都一样高兴 ⑷ 当whether 和or 连用表示明确的选择时，只用whether 不用if 。 如:He asked me whether I wanted to go there by train or by bus.他问我是想乘火车还是坐公共汽车去那里。 He hesitated about whether he should drive or take the train.他开车去还是坐火车去, 犹豫不决 注:whether 和or 连用还可以引导让步状语从句,此时也不用if 。 如：We'll go on with the work, whether we can find the necessary tools or not. 不管我们能否找到所需的工具,我们要把这件工作做下去。 Whether or not it rains / Whether it rains or not, we're playing football on Saturday. 无论下不下雨, 我们星期六一定踢足球. ⑸ 动词discuss ，decide,consider 等后习惯上也常用Whether 引导从句，不用if 。 They discussed whether they should leave at once. 他们讨论了是否应该马上离开。 We discussed whether the house should be sold. 我们讨论了这房子是否应卖掉。 3.表语从句用whether 引导不用if. 如:①The doubt was whether you had broken the beautiful vase. 疑问是你是否打坏了这只漂亮的花瓶。 4. 同位语从句用whether 引导不用if . 如:①The question whether we'll build another lecture building hasn't been settled. 是否要另建一幢教学楼的问题还未决定。 5. 在动词不定式之前，只能用whether ，不能用if 。 如:①The question is whether to go to Munich or Vienna. 问题是去慕尼黑还是去维也纳. ②She doesn't knows whether to get married now or wait. 是否现在结婚或是等待她不知道。 ③We were wondering whether to go today or tomorrow. 我们弄不清是今天走还是明天走. ④I'm not sure whether to resign or stay on. 我拿不准主意是辞职还是留任. 强化练习： 1. The question has not been answered ____ Taiwan will be included on the Olympic tor ch relay route. A ．that B ．whether C ．which D ．if 2. You have not yet answered my question _____ I can join in the party tonight or no t. A. whether B. if C. that D. which 3．— I d like to invite you to a party this evening. — Thank you, but _____ I’ll be free I m not sure at the mome nt. A. while B. if C. when D. whether 4．---What are you anxious about? ---___________ A. If we succeed B.That we can succeed C. Do we succeed D.Whether we can s ucceed 5. Only when _____ the painting _____ decide ______the painting is worth buying. A. he sees, he can ,whether B. does he see, can he, if C. he sees, can he ,whether D. sees he, he can,that 6. _____ English is his favourite subject A. I asked him if B. I asked him that whether C. I asked him that D. I asked hi m which 7. _____ they’ll go to the Summer Palace ____ the weather. A. If; depends on B. Whether; depends upon C. Whether; depended on D. If; d epended upon 8.It isn’t quite _____ ______ he will be present at the meeting. A. sure; whether B. sure; if C. certain; whether D. certain; that 9. _____ the 2008 Olympic will be held in Beijing is not known yet. A. Whether B. If C. Whenever D. That 10. No one was sure _____ he would be asked to speak next year. A. when B. whether C. what D. how 11. It is still a question to us all _____ there is any living thing in some other places in the space. A. whether B. which C. what D. where 12. I doubt _____ he will come here on time. A. that B. whether C. when D. where 13. A. but whether C. but how 14. “What did he as A. That B. When C. Where 15. He treated all the people around him,______he knew or he didn't know,______.