跪求虚拟语气的全部情况
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英语
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。）
If it had rained last night (过去), it would be very cold today (现在).
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.
Had you come earlier, you would have met him
=If you had come earlier, you would have met him.
Should it rain, the crops would be saved.
=Were it to rain, the crops would be saved.
注意：
在虚拟语气的从句中，动词'be'的过去时态一律用"were"，不用was， 即在从句中be用were代替。
If I were you, I would go to look for him.
如果我是你，就会去找他。
If he were here, everything would be all right.
如果他在这儿，一切都会好的。
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.
It is necessary that he (should) come to our meeting tomorrow.
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
I suggest that we (should) hold a meeting next week.
He insisted that he (should ) be sent there.
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.
判断改错:
（错） You pale face suggests that you (should) be ill.
(对) Your pale face suggests that you are ill.
(错) I insisted that you ( should) be wrong.
(对) I insisted that you were wrong.
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。
My idea is that we (should) get more people to attend the conference.
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。
He wished he hadn't said that. 他希望他没讲那样的话。
I wish it would rain tomorrow. 我希望明天下雨就好了。
2）Wish to do表达法。
Wish sb / sth to do
I wish to see the manager. = I want to see the manager.
I wish the manager to be informed at once. (= I want the manager to be informed at once.)
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。
I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
If only the alarm clock had rung. 当时闹钟响了，就好了。
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.
It is high time that the children should go 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。
John went to the station with the car to meet Mary, so she didn't need to walk back home. 约翰开车去车站接玛丽，所以她不必步行回家了。
John went to the station with the car to meet Mary, so she needn't have walked back home. 约翰开车去车站接玛丽，所以她本不必步行回家了。 (Mary步行回家，没有遇上John的车。)
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
Top�grade 〔A〕 diamonds had not 〔B〕 increased so sharply 〔C〕 in value in the late seventies 〔D〕 if one company had not controlled almost all of the world’s supply.
3. 与将来的事实相反
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)
We dare not play jokes on Mr. Wang lest he should become angry. (我们不敢跟王先生开玩笑，恐怕他生气。)
He hurried on, lest he should drop out in the forced match. (他加紧步伐，生怕在急行军中掉队。)
Every attention must be paid to him lest he (should) feel that he is inferior to my other guests. (我对他特别关照，唯恐他感觉到比我的其他客人低人一等。)
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。)
We could have done better under more favorable conditions.(假设我们有更有利条件，我们还会做得更好。)
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。) I am very sorry if I had done anything wrong to you, but I am sure that it was unintentional.(如果我当时对你作错了什么事，我向你表示抱歉。但我敢保证我不是故意的。)
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”)
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。) / I wish I didn't say that. (要是我不说这件事就好了。) / I wished I were not so worried. Then I would not have had the accident. ( 我要是不那么忧郁就好了，那也就不会发生那场事故了。)
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。) / She wishes you wouldn't go. (她希望你不要走。)
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”。)
He pursued various theories for several days until I suggested we take the toy apart to see how it did work. (他费了几天功夫寻找理论根据，直到我建议拆开看看它是如何转动的。)
One can suggest that students should spend two or three years in an English�speaking country. (我们建议学生应在说英语的国家呆上两三年。)
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 … .
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。
We advise that steps(should)be taken at once．我们建议要立刻采取措施。
They insisted that he(should)begin the work at once．他们坚持让他立刻开始工作。
He ordered that aU(should)take part in the work．他下令所有的人都要参加这项工作。
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：
He asked that he be given an opportunity to try．他要求给他一个尝试的机会。
I move that the money be used for books． 我提议把这笔钱用于买书。
They urged that we take action on this matter immediately．他们极力主张我们对这件事立即采取行动。
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 1 were／Was as strong as you．我要是像你一样强壮就好了。
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：
1 wish he would try again．我希望他再试一下。
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。
Don’t come tomorrow．I’d rather you came nextweekend．明天别来，我宁愿你下个周末来。
一Shall l open a window?我开窗行吗？ 一I’d rather you didn’t．你最好别开。
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：
h is desired that everyone(should)get erything ready bY toniShL要求每一个人在今晚之前要将一切准备好。
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 important and necessary that we should master a foreign language．掌握一门外语对我们来说是重要的和必要的。
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)
His suggestion that the meeting(shoald)be held in this room has been accepted．他的关于在这个房间召开会议的建议被采纳了。(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。
We would go with you if we had time．如果我们有时间的话，就和你一道去了。
We could ask him if he were here．如果他在这儿，我们就可以问他了。
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：
If he had seen you yesterday，he would have asked you about it如果昨天他见到你，他就会问你那件事了。
If you had come earlier，you would have met him．如果你早点儿来，就会遇到他了。
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 he came tomorrow,he would find me in the schoo1．如果他明天来的话，会在学校找到我。
If it should rain，the crops would be saved．如果下雨，庄稼就有救了。
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。
Had you arrived five minutes earlier，you could have seen them off．如果你早到五分钟，
你就可以给他们送行了。
Should he come，tell him to ring me up．如果他来的话，叫他打电话给我。
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。
She explained again and again in case he (should)misunderstand her．她解释了一遍又一遍，以免他误解她。
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 stayed at home for a few days so that
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 if 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)
He speaks English as well as ifhe hadstudied in England．他英语说得这么好，好像他去英国学过英语似的。(实际上他没有在英国学过英语)
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。
We were surprised that she should be so stubbom．她这么固执让我们感到奇怪。
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绪。
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。）
If it had rained last night (过去), it would be very cold today (现在).
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.
Had you come earlier, you would have met him
=If you had come earlier, you would have met him.
Should it rain, the crops would be saved.
=Were it to rain, the crops would be saved.
注意：
在虚拟语气的从句中，动词'be'的过去时态一律用"were"，不用was， 即在从句中be用were代替。
If I were you, I would go to look for him.
如果我是你，就会去找他。
If he were here, everything would be all right.
如果他在这儿，一切都会好的。
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.
It is necessary that he (should) come to our meeting tomorrow.
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
I suggest that we (should) hold a meeting next week.
He insisted that he (should ) be sent there.
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.
判断改错:
（错） You pale face suggests that you (should) be ill.
(对) Your pale face suggests that you are ill.
(错) I insisted that you ( should) be wrong.
(对) I insisted that you were wrong.
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。
My idea is that we (should) get more people to attend the conference.
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。
He wished he hadn't said that. 他希望他没讲那样的话。
I wish it would rain tomorrow. 我希望明天下雨就好了。
2）Wish to do表达法。
Wish sb / sth to do
I wish to see the manager. = I want to see the manager.
I wish the manager to be informed at once. (= I want the manager to be informed at once.)
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。
I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
If only the alarm clock had rung. 当时闹钟响了，就好了。
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.
It is high time that the children should go 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。
John went to the station with the car to meet Mary, so she didn't need to walk back home. 约翰开车去车站接玛丽，所以她不必步行回家了。
John went to the station with the car to meet Mary, so she needn't have walked back home. 约翰开车去车站接玛丽，所以她本不必步行回家了。 (Mary步行回家，没有遇上John的车。)
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
Top�grade 〔A〕 diamonds had not 〔B〕 increased so sharply 〔C〕 in value in the late seventies 〔D〕 if one company had not controlled almost all of the world’s supply.
3. 与将来的事实相反
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)
We dare not play jokes on Mr. Wang lest he should become angry. (我们不敢跟王先生开玩笑，恐怕他生气。)
He hurried on, lest he should drop out in the forced match. (他加紧步伐，生怕在急行军中掉队。)
Every attention must be paid to him lest he (should) feel that he is inferior to my other guests. (我对他特别关照，唯恐他感觉到比我的其他客人低人一等。)
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。)
We could have done better under more favorable conditions.(假设我们有更有利条件，我们还会做得更好。)
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。) I am very sorry if I had done anything wrong to you, but I am sure that it was unintentional.(如果我当时对你作错了什么事，我向你表示抱歉。但我敢保证我不是故意的。)
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”)
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。) / I wish I didn't say that. (要是我不说这件事就好了。) / I wished I were not so worried. Then I would not have had the accident. ( 我要是不那么忧郁就好了，那也就不会发生那场事故了。)
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。) / She wishes you wouldn't go. (她希望你不要走。)
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”。)
He pursued various theories for several days until I suggested we take the toy apart to see how it did work. (他费了几天功夫寻找理论根据，直到我建议拆开看看它是如何转动的。)
One can suggest that students should spend two or three years in an English�speaking country. (我们建议学生应在说英语的国家呆上两三年。)
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 … .
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。
We advise that steps(should)be taken at once．我们建议要立刻采取措施。
They insisted that he(should)begin the work at once．他们坚持让他立刻开始工作。
He ordered that aU(should)take part in the work．他下令所有的人都要参加这项工作。
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：
He asked that he be given an opportunity to try．他要求给他一个尝试的机会。
I move that the money be used for books． 我提议把这笔钱用于买书。
They urged that we take action on this matter immediately．他们极力主张我们对这件事立即采取行动。
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 1 were／Was as strong as you．我要是像你一样强壮就好了。
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：
1 wish he would try again．我希望他再试一下。
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。
Don’t come tomorrow．I’d rather you came nextweekend．明天别来，我宁愿你下个周末来。
一Shall l open a window?我开窗行吗？ 一I’d rather you didn’t．你最好别开。
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：
h is desired that everyone(should)get erything ready bY toniShL要求每一个人在今晚之前要将一切准备好。
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 important and necessary that we should master a foreign language．掌握一门外语对我们来说是重要的和必要的。
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)
His suggestion that the meeting(shoald)be held in this room has been accepted．他的关于在这个房间召开会议的建议被采纳了。(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。
We would go with you if we had time．如果我们有时间的话，就和你一道去了。
We could ask him if he were here．如果他在这儿，我们就可以问他了。
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：
If he had seen you yesterday，he would have asked you about it如果昨天他见到你，他就会问你那件事了。
If you had come earlier，you would have met him．如果你早点儿来，就会遇到他了。
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 he came tomorrow,he would find me in the schoo1．如果他明天来的话，会在学校找到我。
If it should rain，the crops would be saved．如果下雨，庄稼就有救了。
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。
Had you arrived five minutes earlier，you could have seen them off．如果你早到五分钟，
你就可以给他们送行了。
Should he come，tell him to ring me up．如果他来的话，叫他打电话给我。
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。
She explained again and again in case he (should)misunderstand her．她解释了一遍又一遍，以免他误解她。
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 stayed at home for a few days so that
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 if 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)
He speaks English as well as ifhe hadstudied in England．他英语说得这么好，好像他去英国学过英语似的。(实际上他没有在英国学过英语)
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。
We were surprised that she should be so stubbom．她这么固执让我们感到奇怪。
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绪。
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虚拟语气
注意：条件句分两种，真实条件句和虚拟条件句。只有在虚拟（非真实）条件句中，才用虚拟语气，而在真实条件句中，要用陈述语气。
构成 条件从句 主句
时态 If＋一般现在时 主语＋shall/will+动词原形
例句 If he comes, he will take us to the zoo.
1） If it is sunny tomorrow , we’ll go to the zoo.
2）If I were you , I would go at once.
3). He doesn’t know if he should bring a present.（宾语从句，if表示是否）
拟语气表示和现实的事实相反时，从句用一般过时。
主句用 “should/would/could/ might +动词原形。
句型 ： 条件从句 一般过去时
主句 should( would) +动词原形
1.If I had time, I would go for a walk.
2.If I were invited, I would go to the dinner party.
3.If I won a million dollars in the lottery, I would put it in
知识点2.If I were you , I’d wear a shirt and tie.
表示于过去事实相反的假设。
句型： 条件从句 过去完成时
主句 should(would) have+ 过去分词
Eg. If my lawyer had been here last Saturday, he would have prevented me from going.
表示对将来的假想
句型： 条件从句 一般过去时 were+ 不定式 should + 动词原形
主句 should+ 动词原形 would + 动词原形
Eg. If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right
注意：条件句分两种，真实条件句和虚拟条件句。只有在虚拟（非真实）条件句中，才用虚拟语气，而在真实条件句中，要用陈述语气。
构成 条件从句 主句
时态 If＋一般现在时 主语＋shall/will+动词原形
例句 If he comes, he will take us to the zoo.
1） If it is sunny tomorrow , we’ll go to the zoo.
2）If I were you , I would go at once.
3). He doesn’t know if he should bring a present.（宾语从句，if表示是否）
拟语气表示和现实的事实相反时，从句用一般过时。
主句用 “should/would/could/ might +动词原形。
句型 ： 条件从句 一般过去时
主句 should( would) +动词原形
1.If I had time, I would go for a walk.
2.If I were invited, I would go to the dinner party.
3.If I won a million dollars in the lottery, I would put it in
知识点2.If I were you , I’d wear a shirt and tie.
表示于过去事实相反的假设。
句型： 条件从句 过去完成时
主句 should(would) have+ 过去分词
Eg. If my lawyer had been here last Saturday, he would have prevented me from going.
表示对将来的假想
句型： 条件从句 一般过去时 were+ 不定式 should + 动词原形
主句 should+ 动词原形 would + 动词原形
Eg. If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right
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