问题描述：
英语中虚拟语气和情态动词的理解与运用
本人年纪比较小,请说的详细一些,不要太深奥
本人年纪比较小,请说的详细一些,不要太深奥
问题解答：
我来补答
虚拟语气
1） 概念
虚拟语气用来表示说话人的主观愿望或假想,所说的是一个条件,不一定是事实,或与事实相反.
2） 在条件句中的应用
条件句可分为两类,一类为真实条件句,一类为非真实条件句.非真实条件句表示的是假设的或实际可能性不大的情况,故采用虚拟语气.
1.真实条件句
真实条件句用于陈述语气,假设的情况可能发生,其中 if 是如果的意思.
时态关系
句型：条件从句 主句
一般现在时shall/will + 动词原形
If he comes, he will bring his violin.
典型例题
The volleyball match will be put off if it ___.
A. will rain B. rains C. rained D. is rained
答案B.真实条件句主句为将来时,从句用一般现在时.
2） 表示真理时,主句谓语动词便不用shall (will) +动词原形,而直接用一般现在时的动词形式.
2.非真实条件句
1）时态：可以表示过去,现在和将来的情况.它的基本特点是时态退后.
a. 同现在事实相反的假设.
句型 ： 条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
b. 表示于过去事实相反的假设.
句型： 条件从句 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
c. 表示对将来的假想
句型： 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you succeeded, everything would be all right.
3.混合条件句
主句与从句的动作发生在不同的时间,这时主,从句谓语动词的虚拟语气形式因时间不同而不同,这叫做混合条件句.
If you had asked him yesterday, you would know what to do now.
（从句与过去事实相反,主句与现在事实相反.）
4.虚拟条件句的倒装
虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略,再把were, should或had 移到从句句首,实行倒装.
Were they here now, they could help us.
=If they were here now, they could help us.
If I were you, I would go to look for him.
如果我是你,就会去找他.
典型例题
_____ to do the work, I should do it some other day.
A. If were IB. I were C. Were I D. Was I
答案C. 在虚拟条件状语中如果有were, should, had这三个词,通常将if省略,主语提前, 变成 were, should, had +主语的形式.但要注意,在虚拟条件状语从句中,省略连词的倒装形式的句首不能用动词的缩略形式.如我们可说 Were I not to do., 而不能说 Weren't I to do.
5特殊的虚拟语气词：should
1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形, should 可省略.
句型：
(1)suggested
It is (2)important that…+ (should) do
(3) a pity
(1)suggested, ordered, proposed, required, demanded, requested, insisted； + (should) do
(2)important, necessary, natural, strange
a pity, a shame, no wonder
(3)It is suggested that we (should) hold a meeting next week.
2）在宾语从句中的应用
在表示命令、建议、要求等一类动词后面的从句中.
order, suggest, propose, require, demand, request, insist, command, insist + (should) do
注意： 如suggest, insist不表示"建议" 或"坚持要某人做某事时",即它们用于其本意"暗示、表明"、"坚持认为"时,宾语从句用陈述语气.
The guard at gate insisted that everybody obey the rules.
3）在表语从句,同位语从句中的应用
在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气,即（should）+动词原形.
I make a proposal that we (should) hold a meeting next week.
6.wish的用法
1）用于wish后面的从句,表示与事实相反的情况,或表示将来不太可能实现的愿望.其宾语从句的动词形式为：
真实状况 wish后
从句动作先于主句动词动作 过去时 过去完成时
（be的过去式为 were）
从句动作与主句动作同时发生 现在时 过去时
（had + 过去分词）
将来不大可能实现的愿望 将来时 would/could +
动词原形
I wish I were as tall as you. 我希望和你一样高.
2）Wish to do表达法.
Wish sb / sth to do
7.比较if only与only if
only if表示"只有"；if only则表示"如果……就好了".If only也可用于陈述语气.
If only he comes early. 但愿他早点回来.
8.It is (high) time that
It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形,但should不可省略.
It is time that the children went to bed.
9 need "不必做"和"本不该做"
didn't need to do表示： 过去不必做某事, 事实上也没做..
needn't have done表示： 过去不必做某事, 但事实上做了.
典型例题
There was plenty of time. She ___.
A. mustn't have hurried B. couldn't have hurried C. must not hurry D. needn't have hurried
答案D.needn't have done. 意为"本不必",即已经做了某事,而时实际上不必要.
Mustn't have done 用法不正确,对过去发生的事情进行否定性推断应为couldn't have done, "不可能已经". must not do 不可以（用于一般现在时）.
语气是一种动词形式,用以表示说话者的意图或态度.虚拟语气表示说话者的主观愿望、假想和建议等,所说的话有的与现在事实相反,或与过去事实相反,或与将来事实相反或与将来事实可能相反.所以虚拟语气总是与假设条件句用在一起.除了if条件句外,还有几种常用的条件句,短语也可表示条件.此外,上下文也能创造虚拟的语言环境.但有时条件从句与结果主句可能发生时间不一致,有时虚拟语气会出现倒装情况.除了与条件句在一起使用的主句用虚拟语气外,有些宾语从句或表语从句也有用虚拟语气的情况.
I虚拟语气的形式与基本用法
一、虚拟语气的形式
虚拟(条件)语气中,主句与从句中谓语动词的形式可分为下面四类
假设类型
条件从句谓语
动词形式
主语谓语
动词形式
与现在事实相反
动词的过去式(be用were而不用was)
would(第一人称可用should)
+动词原形
与过去事实相反
had+ -ED分词
would(第一人称可用should)
+have + -ED分词
与将来事实相反
were to + 动词原形
would(第一人称可用should)
+动词原形
与将来事实可能相反
should + 动词原形
would(第一人称可用should)
+动词原形
二、虚拟语气的基本用法
1. 与现在的事实相反
1) What type of automobile would you buy ?
〔D〕 if you were free to choose among all the cars available today
2. 与过去的事实相反(有时主句中的should have done表示责备或后悔)
2) ,he would have come to class.
〔D〕 If Mike had been able to finish his homework
3) If the United States had not entered the Second World War,probably the 1940 unemployment rate of 14％ still further.
〔C〕 would have risen
4) Topgrade 〔B〕 increased so sharply
3. 与将来的事实相反
5) The report would be 〔A〕 released last January if new developments had not
6) It is said Tom will go to an appointment tommorrow. If he were to come tomorrow, I ask him to go to your place.
〔B〕 would
7) If you to see Mary,what would you tell her?
〔D〕 were
4. 与将来的事实可能相反
(1) If it should rain tomorrow, I would stay at home. 要是万一 明天下雨,我就呆在家里不出去. 事实上 现在天气很好,明天下雨的可能性应该不大,不过也说不准.
(2) If I should see her next Monday, I would tell her about it. 如果下周一我能见到她的话我就把这件事告诉她.
II 虚拟语气的特殊表现形式
一、表示“好像”：除了if条件从句外,由as if和as though等引导的状语从句表示方式时,意思是“好像”,这时从句中的谓语动词应用虚拟语气.其动词形式用过去时(be用were的形式)表示所说的与现在的事实相反；用过去完成时表示所说的与过去的事实相反
二、特殊连词的需要：lest, for fear that和in case引起的从句(这时谓语多用should＋加动词原形)
He’s working hard for fear that he should fail in the exam. (他加紧学习唯恐考试不及格.)
三、介词短语表示虚拟： 有时假设的情况并不以条件从句表示出来,而是通过一个介词短语来表示,或通过上下文或其他方式表示出来.如 but for, but that…, in case of, otherwise, supposing, under more favourable condition, without 等表示让步假设
He worked very hard; otherwise he might have failed. (他刻苦工作,不然他就失败了.)
2) But for his help,I .
〔A〕 should not have succeeded
3) The complex society of a modern 〔C〕 the art of writing 4) But that he came to help me, I .
〔A〕 could not have succeeded
四、虚拟错综条件句：上面几种假设类型中,主句与从句的谓语动词形式应前后呼应.但是,如果主句与从句的动作发生的时间不一致,谓语动词形式应做适当调整
If I had a bike(now), I would have lent it to you yesterday. 假如我有自行车,昨天早就借给你了.(主句与过去事实相反,从句与现在事实相反.)
5) If the United States had built more homes for poor people in 1955,the housing problems now in some parts of this country so serious.
〔A〕 wouldn’t be
6) If you had not studied the problem carefully until recently .
〔C〕 you would find any difficulty now
五、省略虚拟条件句：虚拟条件从句中的谓语动词如果是were或should(could, might), had等词时,可以省略连词If, 但要将were或should(could, might), had助动词移至主语前形成句子例装(参见第十三章“倒装句”)
7) today, he would get there by Thursday.
〔D〕 Were he to start out.
8) ,John would not have failed.
〔B〕 Had he listened to me
9) I known it,I should have told him.
〔B〕 Had
10) Hadn’t my car broken down,I the train.
〔A〕 should have caught
III 从句中须用虚拟语气的情况
一、在wish的宾语从句中
1. 动词wish后跟由that引导的宾语从句(that经常被省略)要用虚拟语气表示一种不可实现的愿望.宾语从句中用过去时(be 用were的形式)表示与现在事实相反,用过去完成时表示与过去相反
She wishes she had more money. (她真希望有更多的钱.)
2. 当wish的宾语从句表示一种愿望、要求时,可用过去时,也可用would＋动词原形
I wish you would stay here longer. (我希望你在这儿多呆一会.) 3. would rather(宁愿),would sooner(宁愿), had rather(宁愿) 等词或短语后面的从句中的谓语动词应使用一般过去时表示虚拟语气,表示与过去相反的也可用过去完成时
二、在某些特殊概念词的宾语从句中：一些表示提议、主张、要求、命令、紧要等概念的词语,由于它们本身隐含说话者的主观意见,认为某事应该或不应该怎样,这些词语后面的“that”从句应用虚拟语气,且均以“should”表示这种语气,但事实上“should”常被省略,故此从句中谓语动词用原形.这些词可分为下列几类
1. 下列动词后“that”引导的宾语从句
suggest(建议), propose (提议), recommend(建议), move (提议), advise(建议), insist(坚持), urge(极力主张), ask, require, request(要求), demand, desire, order, command(命令), decide, intend(打算), prefer(宁愿), urge(敦促).
When I suggested that he try shaving cream, he said, “The razor and water do the job. ” (当我建议他用刮胡膏时,他说“剃刀和水就行了”.)
2. 下列表示主张、要求、命令、愿望、建议等概念结构后的主语从句或逻辑上的主从结构(如下列形容词作宾语从句的补足语时,这时宾语从句一般用it来代替)：这时that所引导的主语从句中的谓语动词常用“should ＋ 动词原形”或省略should,只用动词原形
it is necessary 【 essential (重要的), vital(极重要的,不可缺少的),important,imperative(必须的),urgent(紧要的),advisable(应该的),proper(适当的),obligatory (必须的),desirable(今人满意的,值得的),appropriate(合适的),fitting (合适的), strange (奇怪)】that…； it is(was, has been) desired 【suggested , requested, ordered , proposed, dicided】 that … .
3. 下列表示主张、要求、命令等概念的名词后面可以跟接“that”引导的表语从句和同位语从句.这种由that引导的从句其谓语动词通常用should＋动词原形或省略should.这类词有：order, request, requiremetn, insistence,suggestion, command, necessity, importance, idea, plan, motion(提议),proposal(建议),recommendation(建议),understanding(协议), resolution(决定,决议)
4. 在expect, believe, think, suspect等动词的否定或疑问形式后的宾语从句,我们经常用“should＋动词原形(或完成形式)”,表示惊奇,怀疑,不满等
I never thought that he should be such a brave young soldier. 我们从来没想到他是个如此勇敢的小战士.
5. 另外,在“开放式条件句”(open conditional clause)和让步状语从句中should是被省略了的.在这种情况下,如果if省略,动词be与主语的位置要倒装
If any person be guilty of a crime, the court shall have the right to appeal. (任何人犯罪,法院有权起诉.)
Whether she be right or wrong, she will have my unanswering support. (不管她是对还是错,我都会支持她的.)
但如果把引导词去掉,我们就要用倒装句,如上述几句可变为
Be any person guilty of a crime, the court shall have the right to appeal.
Be she right or wrong, she will have my unanswering support.
三、it is (high) time, 〔该(必须)做……〕等词或短语后面的 从句 中的谓语动词应使用过去时表示虚拟语气
It is high time that you went home. (你们现在必须回家了.)
It is high time that this wrong spending .
〔C〕 was checked
此外,还有省去了结果主句的虚拟结构,一般表示愿望,如： If only I were five years younger! (要是能年轻5岁就好了.) 虚拟语气是以动词的特殊形式来说明句中所叙述的内容不是事实,或是不可能发生的事情,而是一种愿望、建议或是与事实相反的一种假设.虚拟语气通常出现在各种主从复合句中.
一、在宾语从句中
1．当主句的谓语动词为“suggest,propose,advise,insist,order,demand,require,request, desire’’等表示“建议”、“命令”、“请求”和“要求”的动词时,其后的宾语从句中要用虚拟语气“should+动词原形”(在美国英语中 should省略).例如：
I suggest that we(should)hold a meeting tonight．我建议我们今晚开个会.
另外,当主句动词为“ask,move,urse”等意为 “要求”、 “提议”和“极力主张”时,其宾语从句也常用虚拟语气.例如：
I move that the money be used for books． 我提议把这笔钱用于买书.
2．当主句动词为wish,表示“但愿……”,“要是……该多好叼”之意时,其后的宾语从句有以下三种虚拟语气形式.
①动词用过去式来说明与现在的事实相反(BE动词常用were,但有时也可用was).例如：
1 wish l remembered his address．我要是记住他的地址就好了.
有时；为了强调现在状态下能发生某种情况或进行某项动作,从句中的动词也可用过去进行式.例如：
1 wish it wasn’t raining．要是天不下雨就好
了.
②动词用过去完成式说明与过去的事实相反.例如：
We wish we had paid more attention to our pronunciation．我们以前要是能更注意我们的发音就好了.
He wished he had stayed at home.他但愿他呆在了家里.
③情态动词“would,could,might”等后接动词原形,表示对将来的希望(通常不用should).例如：
We wish he could come．我们希望他能来.
3．在prefer之后的宾语从句中用“should+动词原形”(should可省略).例如：
We prefer that the plan(should)be fully discussed before being put into execution．我们希望在计划实施之前进行认真的讨论.
4．在would rather之后的宾语从句中,其动词用虚拟语气,表示句子的主语(某人)宁愿让另一人做某事.
①用动词过去式表示现在或将来要做的事.例如：
I’d rather you went home now．我宁愿让你现在就回家.
②用动词的过去完成式表示过去的动作.
例如：
I’d rather you hadn’t done that．我真希望(宁愿)你没做过那件事.
二、在主语从句中
1．在句型“h is／was+过去分词+that从句”中,当过去分词为“suggested,ordered,desired,insisted, required,demanded,requested,decided,proposed,urged’’等时,从句中要用“should+动词原形”(should可省略).例如：
It is requested that Miss Zhang(should) give a performance at the party．请求张小姐在晚会上表演一个节目.
2．在句型“h is／Was+形容词+that从句”中,当形容词为“important,necessary,strange,natural’’等时,从句中要用“should+动词原形”(should可省略).例如：
It is strange that he (should) refuse your help．他竟然拒绝你们的帮助,真奇怪.
3．在句型“h is／was+名词+that从句” 中,当名词为“a pity,a shame,no wonder’等时,从句中要用“should+动词原形”(should可省略).例如：
It is a great pity that he should be sO selfish.真遗憾,他竟然那么自私.
三、在同位语从句或表语从句中
在名词“suggestion,proposal,idea,plan,order,advice’’等后面的同位语从句或表语从句中,用“should+动词原形”(should可省略).例如：
I made a proposal that we(should)hold a meeting next week．我提出了我们下个星期开会的建议.(同位语从句)
My idea is that we(should)get more people to attend the conference．我的想法是我们多找些人来参加会议.(表语从句)
四、在定语从句中
在句型“h is(high)time+(that)从句”中,谓语须用虚拟语气.用过去式表示现在或将来的意念,意为“现在是该做某事的时候了”.
例如：
h iS(hieh)time(that)we went home．我们该回家了.
五、在状语从句中
1．在假设条件句的if条件从句中
假设条件句一般是由“if引导的条件从句+主句”构成.if从句中的谓语动词要用虚拟语气的形式.if从句的假设可以是与现在事实相反的条件、与过去事实相反的条件或者与将来不太可能成为事实的条件.下面分述表示这三种条件的if从句的结构：
①与现在的事实相反,其句子结构为“If+主语+were／谓语动词的过去式”.例如：
If 1 were you,I shouldn’t do that．如果我是你,就不会做那件事了.
②与过去的事实相反,其句子结构为“If十主语+谓语动词的过去完成式”.例如：
1 would have called you if I had known your telephone number．如果我知道你的电话号码,就打电话给你了.
③表示将来不太可能实现的条件,其句子结构为“If+主语+动词过去式／were to+动词原形／should+动词原形”.例如：
If it were to snow tomorrow,they would not go out．如果明天下雪,他们就不出去了.
注：在if从句中,如果含有“were,should,had’’时,可省去if而将“were,should,had’’置于句首,构成倒装句.例如：
Were l in your position,1 would go．如果我处在你的位子上,我就走了.
2．在目的状语从句中
①在由lest
和in case等引导的目的状语从句中,用“should+动词原形” (should可省略).例如：
He ran away lest he(should)be seen．他跑走了,以免被人看到.
in case等引导的目的状语从句中的谓语有时也可用陈述语气.此时,从句表示的就是真实情况,而不是虚拟情况.例如：
Take warm clothes in case the weather iS cold．带上厚衣服,以防天气变冷.
②在由“so that…”和“in order that…”
引导的目的从句中,要用“can／could／may／might／would+动词原形”,以表示目的并非事实.例如：
she might／could take care of her sick mother． 她在家呆了几天,以便照顾她生病的母亲.
③在由“for fear that…”引导的从句中,用“should+动词原形”(有时也可用may／might／would).例如：
He worked hard for fear that he should fail．他努力学习,害怕考试不及格.
3．在方式状语从句中
由as if和as though等引导的方式状语从句中,如果从句所表达的情况是虚拟的,则①常用动词的过去式来表示与现在或当时的情况相
反；如果是BE动词,则用were；②常用过去完成式来表示与过去的情况相反.例如：
She loves the child as i厂he were her own．她爱这孩子就好像是她亲生的.
(实际上不是她亲生的孩子)
Holding his head high,he walked past the pole and the soldiers as if they didn’t exist．他昂着头从旗杆和卫兵身旁走过,就像他们不存在似的.(实际上他们是存在的)
4．在原因状语从句中
在“I’m sorry that．—／We were surprised that一．／They were disappointed that．．．”等引导的表示原因的状语从句中,用“should十动词原形”.例如：
I’m sorry that he should be in such poor health．他的身体这么差让我很难过.
上述句子有时也可以用陈述语气,但这仅表示所叙述的是事实,而不表示讲话人的情
情态动词
情态动词是一种本身有一定的词义,但要与不带to的普通动词的不定式一起使用,给谓语动词增添情态色彩,表示说话人对有关行为或事物的态度和看法,认为其可能、应该或必要等.
[编辑本段]分类：
情态动词有四类：
①只做情态动词：must,can(could),may(might),ought to
②可做情态动词又可做实义动词：need,dare
③可做情态动词又可做助动词：shall(should),will(would)
④具有情态动词特征：have(had) to,used to
[编辑本段]位置:
情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前.
I can see you. Come here.
He must have been away.
How dare you treat us like that!
!
特点:
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 "not". 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去,现在或将来.情态动词属非及物动词,故没有被动语态.
He could be here soon.
他很快就来.
We can't carry the heavy box.
I'm sorry I can't help you.
基本助动词与情态助动词最主要的区别之一是,基本助动词本身没有词义,而情态助动词则有自己的词义,能表示说话人对有关动作或状态的看法,或表示主观设想：
What have you been doing since? （构成完成进行体,本身无词义）
I am afraid I must be going. （一定要）
You may have read some account of the matter. （或许已经）
1） 概念
虚拟语气用来表示说话人的主观愿望或假想,所说的是一个条件,不一定是事实,或与事实相反.
2） 在条件句中的应用
条件句可分为两类,一类为真实条件句,一类为非真实条件句.非真实条件句表示的是假设的或实际可能性不大的情况,故采用虚拟语气.
1.真实条件句
真实条件句用于陈述语气,假设的情况可能发生,其中 if 是如果的意思.
时态关系
句型：条件从句 主句
一般现在时shall/will + 动词原形
If he comes, he will bring his violin.
典型例题
The volleyball match will be put off if it ___.
A. will rain B. rains C. rained D. is rained
答案B.真实条件句主句为将来时,从句用一般现在时.
2） 表示真理时,主句谓语动词便不用shall (will) +动词原形,而直接用一般现在时的动词形式.
2.非真实条件句
1）时态：可以表示过去,现在和将来的情况.它的基本特点是时态退后.
a. 同现在事实相反的假设.
句型 ： 条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
b. 表示于过去事实相反的假设.
句型： 条件从句 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
c. 表示对将来的假想
句型： 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you succeeded, everything would be all right.
3.混合条件句
主句与从句的动作发生在不同的时间,这时主,从句谓语动词的虚拟语气形式因时间不同而不同,这叫做混合条件句.
If you had asked him yesterday, you would know what to do now.
（从句与过去事实相反,主句与现在事实相反.）
4.虚拟条件句的倒装
虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略,再把were, should或had 移到从句句首,实行倒装.
Were they here now, they could help us.
=If they were here now, they could help us.
If I were you, I would go to look for him.
如果我是你,就会去找他.
典型例题
_____ to do the work, I should do it some other day.
A. If were IB. I were C. Were I D. Was I
答案C. 在虚拟条件状语中如果有were, should, had这三个词,通常将if省略,主语提前, 变成 were, should, had +主语的形式.但要注意,在虚拟条件状语从句中,省略连词的倒装形式的句首不能用动词的缩略形式.如我们可说 Were I not to do., 而不能说 Weren't I to do.
5特殊的虚拟语气词：should
1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形, should 可省略.
句型：
(1)suggested
It is (2)important that…+ (should) do
(3) a pity
(1)suggested, ordered, proposed, required, demanded, requested, insisted； + (should) do
(2)important, necessary, natural, strange
a pity, a shame, no wonder
(3)It is suggested that we (should) hold a meeting next week.
2）在宾语从句中的应用
在表示命令、建议、要求等一类动词后面的从句中.
order, suggest, propose, require, demand, request, insist, command, insist + (should) do
注意： 如suggest, insist不表示"建议" 或"坚持要某人做某事时",即它们用于其本意"暗示、表明"、"坚持认为"时,宾语从句用陈述语气.
The guard at gate insisted that everybody obey the rules.
3）在表语从句,同位语从句中的应用
在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气,即（should）+动词原形.
I make a proposal that we (should) hold a meeting next week.
6.wish的用法
1）用于wish后面的从句,表示与事实相反的情况,或表示将来不太可能实现的愿望.其宾语从句的动词形式为：
真实状况 wish后
从句动作先于主句动词动作 过去时 过去完成时
（be的过去式为 were）
从句动作与主句动作同时发生 现在时 过去时
（had + 过去分词）
将来不大可能实现的愿望 将来时 would/could +
动词原形
I wish I were as tall as you. 我希望和你一样高.
2）Wish to do表达法.
Wish sb / sth to do
7.比较if only与only if
only if表示"只有"；if only则表示"如果……就好了".If only也可用于陈述语气.
If only he comes early. 但愿他早点回来.
8.It is (high) time that
It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形,但should不可省略.
It is time that the children went to bed.
9 need "不必做"和"本不该做"
didn't need to do表示： 过去不必做某事, 事实上也没做..
needn't have done表示： 过去不必做某事, 但事实上做了.
典型例题
There was plenty of time. She ___.
A. mustn't have hurried B. couldn't have hurried C. must not hurry D. needn't have hurried
答案D.needn't have done. 意为"本不必",即已经做了某事,而时实际上不必要.
Mustn't have done 用法不正确,对过去发生的事情进行否定性推断应为couldn't have done, "不可能已经". must not do 不可以（用于一般现在时）.
语气是一种动词形式,用以表示说话者的意图或态度.虚拟语气表示说话者的主观愿望、假想和建议等,所说的话有的与现在事实相反,或与过去事实相反,或与将来事实相反或与将来事实可能相反.所以虚拟语气总是与假设条件句用在一起.除了if条件句外,还有几种常用的条件句,短语也可表示条件.此外,上下文也能创造虚拟的语言环境.但有时条件从句与结果主句可能发生时间不一致,有时虚拟语气会出现倒装情况.除了与条件句在一起使用的主句用虚拟语气外,有些宾语从句或表语从句也有用虚拟语气的情况.
I虚拟语气的形式与基本用法
一、虚拟语气的形式
虚拟(条件)语气中,主句与从句中谓语动词的形式可分为下面四类
假设类型
条件从句谓语
动词形式
主语谓语
动词形式
与现在事实相反
动词的过去式(be用were而不用was)
would(第一人称可用should)
+动词原形
与过去事实相反
had+ -ED分词
would(第一人称可用should)
+have + -ED分词
与将来事实相反
were to + 动词原形
would(第一人称可用should)
+动词原形
与将来事实可能相反
should + 动词原形
would(第一人称可用should)
+动词原形
二、虚拟语气的基本用法
1. 与现在的事实相反
1) What type of automobile would you buy ?
〔D〕 if you were free to choose among all the cars available today
2. 与过去的事实相反(有时主句中的should have done表示责备或后悔)
2) ,he would have come to class.
〔D〕 If Mike had been able to finish his homework
3) If the United States had not entered the Second World War,probably the 1940 unemployment rate of 14％ still further.
〔C〕 would have risen
4) Topgrade 〔B〕 increased so sharply
3. 与将来的事实相反
5) The report would be 〔A〕 released last January if new developments had not
6) It is said Tom will go to an appointment tommorrow. If he were to come tomorrow, I ask him to go to your place.
〔B〕 would
7) If you to see Mary,what would you tell her?
〔D〕 were
4. 与将来的事实可能相反
(1) If it should rain tomorrow, I would stay at home. 要是万一 明天下雨,我就呆在家里不出去. 事实上 现在天气很好,明天下雨的可能性应该不大,不过也说不准.
(2) If I should see her next Monday, I would tell her about it. 如果下周一我能见到她的话我就把这件事告诉她.
II 虚拟语气的特殊表现形式
一、表示“好像”：除了if条件从句外,由as if和as though等引导的状语从句表示方式时,意思是“好像”,这时从句中的谓语动词应用虚拟语气.其动词形式用过去时(be用were的形式)表示所说的与现在的事实相反；用过去完成时表示所说的与过去的事实相反
二、特殊连词的需要：lest, for fear that和in case引起的从句(这时谓语多用should＋加动词原形)
He’s working hard for fear that he should fail in the exam. (他加紧学习唯恐考试不及格.)
三、介词短语表示虚拟： 有时假设的情况并不以条件从句表示出来,而是通过一个介词短语来表示,或通过上下文或其他方式表示出来.如 but for, but that…, in case of, otherwise, supposing, under more favourable condition, without 等表示让步假设
He worked very hard; otherwise he might have failed. (他刻苦工作,不然他就失败了.)
2) But for his help,I .
〔A〕 should not have succeeded
3) The complex society of a modern 〔C〕 the art of writing 4) But that he came to help me, I .
〔A〕 could not have succeeded
四、虚拟错综条件句：上面几种假设类型中,主句与从句的谓语动词形式应前后呼应.但是,如果主句与从句的动作发生的时间不一致,谓语动词形式应做适当调整
If I had a bike(now), I would have lent it to you yesterday. 假如我有自行车,昨天早就借给你了.(主句与过去事实相反,从句与现在事实相反.)
5) If the United States had built more homes for poor people in 1955,the housing problems now in some parts of this country so serious.
〔A〕 wouldn’t be
6) If you had not studied the problem carefully until recently .
〔C〕 you would find any difficulty now
五、省略虚拟条件句：虚拟条件从句中的谓语动词如果是were或should(could, might), had等词时,可以省略连词If, 但要将were或should(could, might), had助动词移至主语前形成句子例装(参见第十三章“倒装句”)
7) today, he would get there by Thursday.
〔D〕 Were he to start out.
8) ,John would not have failed.
〔B〕 Had he listened to me
9) I known it,I should have told him.
〔B〕 Had
10) Hadn’t my car broken down,I the train.
〔A〕 should have caught
III 从句中须用虚拟语气的情况
一、在wish的宾语从句中
1. 动词wish后跟由that引导的宾语从句(that经常被省略)要用虚拟语气表示一种不可实现的愿望.宾语从句中用过去时(be 用were的形式)表示与现在事实相反,用过去完成时表示与过去相反
She wishes she had more money. (她真希望有更多的钱.)
2. 当wish的宾语从句表示一种愿望、要求时,可用过去时,也可用would＋动词原形
I wish you would stay here longer. (我希望你在这儿多呆一会.) 3. would rather(宁愿),would sooner(宁愿), had rather(宁愿) 等词或短语后面的从句中的谓语动词应使用一般过去时表示虚拟语气,表示与过去相反的也可用过去完成时
二、在某些特殊概念词的宾语从句中：一些表示提议、主张、要求、命令、紧要等概念的词语,由于它们本身隐含说话者的主观意见,认为某事应该或不应该怎样,这些词语后面的“that”从句应用虚拟语气,且均以“should”表示这种语气,但事实上“should”常被省略,故此从句中谓语动词用原形.这些词可分为下列几类
1. 下列动词后“that”引导的宾语从句
suggest(建议), propose (提议), recommend(建议), move (提议), advise(建议), insist(坚持), urge(极力主张), ask, require, request(要求), demand, desire, order, command(命令), decide, intend(打算), prefer(宁愿), urge(敦促).
When I suggested that he try shaving cream, he said, “The razor and water do the job. ” (当我建议他用刮胡膏时,他说“剃刀和水就行了”.)
2. 下列表示主张、要求、命令、愿望、建议等概念结构后的主语从句或逻辑上的主从结构(如下列形容词作宾语从句的补足语时,这时宾语从句一般用it来代替)：这时that所引导的主语从句中的谓语动词常用“should ＋ 动词原形”或省略should,只用动词原形
it is necessary 【 essential (重要的), vital(极重要的,不可缺少的),important,imperative(必须的),urgent(紧要的),advisable(应该的),proper(适当的),obligatory (必须的),desirable(今人满意的,值得的),appropriate(合适的),fitting (合适的), strange (奇怪)】that…； it is(was, has been) desired 【suggested , requested, ordered , proposed, dicided】 that … .
3. 下列表示主张、要求、命令等概念的名词后面可以跟接“that”引导的表语从句和同位语从句.这种由that引导的从句其谓语动词通常用should＋动词原形或省略should.这类词有：order, request, requiremetn, insistence,suggestion, command, necessity, importance, idea, plan, motion(提议),proposal(建议),recommendation(建议),understanding(协议), resolution(决定,决议)
4. 在expect, believe, think, suspect等动词的否定或疑问形式后的宾语从句,我们经常用“should＋动词原形(或完成形式)”,表示惊奇,怀疑,不满等
I never thought that he should be such a brave young soldier. 我们从来没想到他是个如此勇敢的小战士.
5. 另外,在“开放式条件句”(open conditional clause)和让步状语从句中should是被省略了的.在这种情况下,如果if省略,动词be与主语的位置要倒装
If any person be guilty of a crime, the court shall have the right to appeal. (任何人犯罪,法院有权起诉.)
Whether she be right or wrong, she will have my unanswering support. (不管她是对还是错,我都会支持她的.)
但如果把引导词去掉,我们就要用倒装句,如上述几句可变为
Be any person guilty of a crime, the court shall have the right to appeal.
Be she right or wrong, she will have my unanswering support.
三、it is (high) time, 〔该(必须)做……〕等词或短语后面的 从句 中的谓语动词应使用过去时表示虚拟语气
It is high time that you went home. (你们现在必须回家了.)
It is high time that this wrong spending .
〔C〕 was checked
此外,还有省去了结果主句的虚拟结构,一般表示愿望,如： If only I were five years younger! (要是能年轻5岁就好了.) 虚拟语气是以动词的特殊形式来说明句中所叙述的内容不是事实,或是不可能发生的事情,而是一种愿望、建议或是与事实相反的一种假设.虚拟语气通常出现在各种主从复合句中.
一、在宾语从句中
1．当主句的谓语动词为“suggest,propose,advise,insist,order,demand,require,request, desire’’等表示“建议”、“命令”、“请求”和“要求”的动词时,其后的宾语从句中要用虚拟语气“should+动词原形”(在美国英语中 should省略).例如：
I suggest that we(should)hold a meeting tonight．我建议我们今晚开个会.
另外,当主句动词为“ask,move,urse”等意为 “要求”、 “提议”和“极力主张”时,其宾语从句也常用虚拟语气.例如：
I move that the money be used for books． 我提议把这笔钱用于买书.
2．当主句动词为wish,表示“但愿……”,“要是……该多好叼”之意时,其后的宾语从句有以下三种虚拟语气形式.
①动词用过去式来说明与现在的事实相反(BE动词常用were,但有时也可用was).例如：
1 wish l remembered his address．我要是记住他的地址就好了.
有时；为了强调现在状态下能发生某种情况或进行某项动作,从句中的动词也可用过去进行式.例如：
1 wish it wasn’t raining．要是天不下雨就好
了.
②动词用过去完成式说明与过去的事实相反.例如：
We wish we had paid more attention to our pronunciation．我们以前要是能更注意我们的发音就好了.
He wished he had stayed at home.他但愿他呆在了家里.
③情态动词“would,could,might”等后接动词原形,表示对将来的希望(通常不用should).例如：
We wish he could come．我们希望他能来.
3．在prefer之后的宾语从句中用“should+动词原形”(should可省略).例如：
We prefer that the plan(should)be fully discussed before being put into execution．我们希望在计划实施之前进行认真的讨论.
4．在would rather之后的宾语从句中,其动词用虚拟语气,表示句子的主语(某人)宁愿让另一人做某事.
①用动词过去式表示现在或将来要做的事.例如：
I’d rather you went home now．我宁愿让你现在就回家.
②用动词的过去完成式表示过去的动作.
例如：
I’d rather you hadn’t done that．我真希望(宁愿)你没做过那件事.
二、在主语从句中
1．在句型“h is／was+过去分词+that从句”中,当过去分词为“suggested,ordered,desired,insisted, required,demanded,requested,decided,proposed,urged’’等时,从句中要用“should+动词原形”(should可省略).例如：
It is requested that Miss Zhang(should) give a performance at the party．请求张小姐在晚会上表演一个节目.
2．在句型“h is／Was+形容词+that从句”中,当形容词为“important,necessary,strange,natural’’等时,从句中要用“should+动词原形”(should可省略).例如：
It is strange that he (should) refuse your help．他竟然拒绝你们的帮助,真奇怪.
3．在句型“h is／was+名词+that从句” 中,当名词为“a pity,a shame,no wonder’等时,从句中要用“should+动词原形”(should可省略).例如：
It is a great pity that he should be sO selfish.真遗憾,他竟然那么自私.
三、在同位语从句或表语从句中
在名词“suggestion,proposal,idea,plan,order,advice’’等后面的同位语从句或表语从句中,用“should+动词原形”(should可省略).例如：
I made a proposal that we(should)hold a meeting next week．我提出了我们下个星期开会的建议.(同位语从句)
My idea is that we(should)get more people to attend the conference．我的想法是我们多找些人来参加会议.(表语从句)
四、在定语从句中
在句型“h is(high)time+(that)从句”中,谓语须用虚拟语气.用过去式表示现在或将来的意念,意为“现在是该做某事的时候了”.
例如：
h iS(hieh)time(that)we went home．我们该回家了.
五、在状语从句中
1．在假设条件句的if条件从句中
假设条件句一般是由“if引导的条件从句+主句”构成.if从句中的谓语动词要用虚拟语气的形式.if从句的假设可以是与现在事实相反的条件、与过去事实相反的条件或者与将来不太可能成为事实的条件.下面分述表示这三种条件的if从句的结构：
①与现在的事实相反,其句子结构为“If+主语+were／谓语动词的过去式”.例如：
If 1 were you,I shouldn’t do that．如果我是你,就不会做那件事了.
②与过去的事实相反,其句子结构为“If十主语+谓语动词的过去完成式”.例如：
1 would have called you if I had known your telephone number．如果我知道你的电话号码,就打电话给你了.
③表示将来不太可能实现的条件,其句子结构为“If+主语+动词过去式／were to+动词原形／should+动词原形”.例如：
If it were to snow tomorrow,they would not go out．如果明天下雪,他们就不出去了.
注：在if从句中,如果含有“were,should,had’’时,可省去if而将“were,should,had’’置于句首,构成倒装句.例如：
Were l in your position,1 would go．如果我处在你的位子上,我就走了.
2．在目的状语从句中
①在由lest
和in case等引导的目的状语从句中,用“should+动词原形” (should可省略).例如：
He ran away lest he(should)be seen．他跑走了,以免被人看到.
in case等引导的目的状语从句中的谓语有时也可用陈述语气.此时,从句表示的就是真实情况,而不是虚拟情况.例如：
Take warm clothes in case the weather iS cold．带上厚衣服,以防天气变冷.
②在由“so that…”和“in order that…”
引导的目的从句中,要用“can／could／may／might／would+动词原形”,以表示目的并非事实.例如：
she might／could take care of her sick mother． 她在家呆了几天,以便照顾她生病的母亲.
③在由“for fear that…”引导的从句中,用“should+动词原形”(有时也可用may／might／would).例如：
He worked hard for fear that he should fail．他努力学习,害怕考试不及格.
3．在方式状语从句中
由as if和as though等引导的方式状语从句中,如果从句所表达的情况是虚拟的,则①常用动词的过去式来表示与现在或当时的情况相
反；如果是BE动词,则用were；②常用过去完成式来表示与过去的情况相反.例如：
She loves the child as i厂he were her own．她爱这孩子就好像是她亲生的.
(实际上不是她亲生的孩子)
Holding his head high,he walked past the pole and the soldiers as if they didn’t exist．他昂着头从旗杆和卫兵身旁走过,就像他们不存在似的.(实际上他们是存在的)
4．在原因状语从句中
在“I’m sorry that．—／We were surprised that一．／They were disappointed that．．．”等引导的表示原因的状语从句中,用“should十动词原形”.例如：
I’m sorry that he should be in such poor health．他的身体这么差让我很难过.
上述句子有时也可以用陈述语气,但这仅表示所叙述的是事实,而不表示讲话人的情
情态动词
情态动词是一种本身有一定的词义,但要与不带to的普通动词的不定式一起使用,给谓语动词增添情态色彩,表示说话人对有关行为或事物的态度和看法,认为其可能、应该或必要等.
[编辑本段]分类：
情态动词有四类：
①只做情态动词：must,can(could),may(might),ought to
②可做情态动词又可做实义动词：need,dare
③可做情态动词又可做助动词：shall(should),will(would)
④具有情态动词特征：have(had) to,used to
[编辑本段]位置:
情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前.
I can see you. Come here.
He must have been away.
How dare you treat us like that!
!
特点:
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 "not". 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去,现在或将来.情态动词属非及物动词,故没有被动语态.
He could be here soon.
他很快就来.
We can't carry the heavy box.
I'm sorry I can't help you.
基本助动词与情态助动词最主要的区别之一是,基本助动词本身没有词义,而情态助动词则有自己的词义,能表示说话人对有关动作或状态的看法,或表示主观设想：
What have you been doing since? （构成完成进行体,本身无词义）
I am afraid I must be going. （一定要）
You may have read some account of the matter. （或许已经）
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