6. 在if only感叹句中

if only表示“但愿……”，“要是……就好了”，句中的谓语动词要用虚拟语气。其构成的方法与wish后的宾语从句基本相同。

If only Xiao Hua’s mother were still alive!

If only I had known the answer when my teacher questioned me。

If only I could fly to the moon in Shenzhou Ⅷ spaceship。

5. 在It is (high) time(that)…定语从句中，谓语用过去时或用should+动词原形。should不可省略。

It’s high time that we devoted/should devote our time to preparing for the coming exam。

4.在in case, in order that目的状语从句中

在in case 引导的目的状语从句中，谓语动词用“should+动词原形”;在so that, in order that 等引导的目的状语从句中，谓语动词除了用“should+动词原形”外，还可用“might/could/would+动词原形”。

In case you should need any help, here’s my number。

In order that training should be effective it must be planned systematically。

I took a taxi so that I would/could/might be in time for the appointment。

③表示一种假设在将来实现的可能性很小或者根本无法实现，从句谓语动词可用三种形式：①动词过去式 ②were to +动词原形 ③should+动词原形，主句谓语动词用：should (would, could, might)+动词原形。

⑵ 省略连词if 的虚拟条件句中

如果把连接条件从句的连词if省略，必须将从句的谓语部分的助动词had, 情态动词should或系动词were等移至主语之前，构成倒装语序。例如：

Had he known my address(=If he had known my address)， he would have visited me earlier。

Should I meet Jay Zhou some day(=If I should meet Jay Zhou some day)， I might tell him that I like him.

Were I you(=If you were I)， I would get on well with my teachers and classmates。

3. 在as if/though 后的方式状语从句中，表示某种情况与现在的事实相反， 谓语动词用过去式;表示即将发生的情况“用情态动词+动词原形”;表示某种的情况有过去的事实相反， 谓语动词用过去完成时。

The coach always treats the players as if they were his own children.

She was suffering from a bad cold. Her head felt as if it would burst。

Gary was behaving as though nothing had happened。

虚拟语气是一种特殊的动词形式，说话人陈述的并不是事实，而是表达一种愿望、假设和猜测等。只有在非真实的条件句中才使用虚拟语气，如果假设的条件有可能实现，用真实条件句。如果假设的条件无法实现或实现的可能性很小，则用虚拟语气。使用虚拟语气的情况主要有下列几种：

1. 虚拟语气在非真实条件句中的运用

(1) if条件状语从句中的虚拟语气

非真实条件句表示不可能实现的或实现的可能性很小假设。条件句与主句皆须用虚拟语气。其虚拟语气的时态形式有三种：

①表示与现在事实相反的假设，从句的谓语动词用“动词过去式(be一般用were)”，主句的谓语动词用“should (would, could, might)+动词原形”。例如：

If you were the UN Secretary General, could you stop the wars on the earth?

If he had a chance, he would/should/ might/could choose to study abroad。

②表示与过去事实相反的假设，从句的谓语动词用“had+过去分词”，主句的谓语动词用“should (would, could, might)+have+过去分词”。

[记忆小窍门]可提到句首的词有三个：had, should和were。谐音记忆：一马当先“还属我”。

⑶含蓄虚拟条件句

有时，可不用条件句表示一个非真实的条件，而用一些介词短语或通过上下文中暗含某种非真实的条件，这种句子叫做“含蓄条件句”。例如：

①通过with, without, but for和动词不定式短语等表示虚拟的条件

She’d look better with shorter hair. =if she had her hair cut shorter

Without your help, we could not have completed the task ahead of time. =If it had not been for your help…

But for the heavy snow, I could have gone on holiday. =If there had not been the heavy snow…

She would be shocked to hear the news. =If she heard the news…

It would be easier to do it in this way. =If you did it in this way…

②句中含有or, or else, otherwise, but等词语，暗示句子的某一部分(前句或后句)需用虚拟语气。

He was on business in Beijing at that time; otherwise he might have helped us。

Luckily Mary telephoned to inform me of the meeting, or would have been I absent。

I should have attended my friend’s wedding ceremony, but I couldn’t afford the time。 　2.虚拟语气在名词性从句中的运用

⑴在主语从句中， 在下面的几种情况下，谓语动词通常用“should +动词原形”

①It is+形容词+that…句型。常见的形容词有important, necessary, natural, funny, strange, surprising, astonishing(令人惊讶的)等。

② It is +名词+that…句型。常见的名词有pity, shame, advice, suggestion, proposal(提议，建议)， requirement, request, desire, order等。

③ It is+动词的过去分词+ that…句型。常见的动词有advise, order, propose, request, suggest, demand, require等。

在以上三种句型中，主语从句的谓语动词要用“should+动词原形”， should可省略。例如：

It is important that we (should) have a good knowledge of computer in modern times。

It is necessary that these useful expressions (should) be learnt by heart。

It is a shame that children (should) be forced to beg in the streets in the capital city。

It's suggested that the school (should) organize an outing when spring comes。

It is required that middle-schools students (should) take at least one-hour exercise every day。

⑵在下列动词后的宾语从句中，谓语动词用“should+动词原形”，should可省略。这类动词有：insist(坚持)， urge (催促)， order(命令)， command(命令)， request(请求，要求)， demand(要求)，require(要求，需要)suggest(建议)，advise(建议)，propose(建议) , recommend(建议， 推荐) 等。

The captain insisted that the wounded soldier (should) be sent to hospital at once。

The policeman demanded the thief (should) tell his name and address。

Doctors strongly recommend that fathers (should) be present at their baby's birth。

If Li Ming had spent more time on her studies, she might/would/could/should have been admitted to Tsinghua University last year。

[记忆小窍门]一个“坚持”和”催促”、二个“命令”， 三个“要求”， 四个“建议”。

⑶在含有advice, order, demand, proposal(提议) requirement, suggestion等名词的表语从句、同位语从句中，谓语动词用“should+动词原形”，should可省略。

The governor gave order that the flood (should) be controlled before dark。

My suggestion is that the project (should) be completed by the end of the year。

在一些名词性从句中，谓语动词用“should+动词原形”或“should +have done”，表示惊讶、意志等感情色彩，译为“竟然，居然”。

I am surprised /shocked that you should speak in such a way。

I find it astonishing that he should be so rude to his mum。

It is strange /surprising that she should not have been invited。

I am glad that your story should have won the first prize。

⑷在wish后的宾语从句中

①表示将来的愿望实现的可能性非常小，wish后的宾语从句的谓语动词用should/would/could/ might+动词原形。

We wish the friendship between the two countries would last forever。

②表示与现在事实相反的愿望，宾语从句的谓语动词用一般过去时(be动词用were)。

②He always wishes he were a millionaire and owned a big house and a sports car.

③表示与过去事实相反的愿望，宾语从句的谓语动词用过去完成时。

③How he wished he hadn’t wasted too much time on playing computer games while at school.

⑸在would rather/would prefer后的宾语从句中

在would rather/would prefer后的宾语从句中，常用过去时表示与现在或将来事实相反的愿望，用过去完成时表示与过去事实相反的愿望。

⑹在would rather/would prefer从句中

①Frankly speaking, I would rather you came tomorrow. The manager isn’t available today。

②I would rather you had gone to the party with me last night. It was really wonderful。

③-Could I smoke here?

-I'd prefer it if you didn’t smoke in front of the children。

依据语境来判断虚拟语气的不同形式是高考试题的主要设题方法之一。在近年的高考试题中，出现了对陈述语气与虚拟语气辨析的考查。虚拟语气在各种从句中的应用是该部分的重点掌握内容。

根据考纲的要求，虚拟语气部分主要考查情态动词的选择、虚拟语气在条件句中、在名词性从句中、在简单句中或在日常交际中的使用等基本用法。

5. (北京市东城区高中示范校2009届高三质量检测) In the earthquake, parents were willing to do they could their children。

A.whatever; save B.whatever; to save

C.what; saving D.what; to save

考点解析：题干中第一空可填whatever，因could后省略了动词do，第二空为动词不定式作目的状语，应填to save，因此最佳答案为A。

4. (2009年郑州市毕业班第一次质量预测) It must be somebody’s, but I don’t know 。

A.who B.which C.whose D.whom

考点解析：句意为“这肯定是某人的，但是我不知道是谁的”，上句中的somebody’s 暗示应选“whose”， 其实是宾语从句whose (it is)的省略。因此最佳答案为C。

3. (2009年郑州市毕业班第二次质量预测) You can go to the party with us if you 。

A.want to B.want to do C.want it D.want to go

考点解析：句意为：“如果你想和我们一起参加派对，你就去吧”。前句出现了动词短语：go to the party with us, 因此在if引导的状语从句中该动词不定式短语被省略，只保留动词不定式的符号to, 因此最佳答案为A。