虛擬語氣是高中英語教學的重點和難點，在高考中雖然出現得不多，但作為一個獨立的語法項目，我們也必須完全掌握這一考點。從高考考查的情況看，三種與事實相反的條件句和主句的基本結構，以及用其他形式代替條件句和虛擬條件句的倒裝是考查的重點，本文擬談高考虛擬語氣的常見考點，以便幫助大家掌握這一語法項目。
01用於條件句
(一)用於if引導的非真實條件句
If I were a boy，I would join the army．
If my brother had taken my advice，he would have succeeded in the competition.
If it were to rain tomorrow ，the football match would be put off．
注意：主句中的should通常用於第一人稱，would／could可以用於各種人稱。
Were I to do the work，I should do it some other day．
If I had his telephone number, I would call him now．
If he had worked hard, he would have been in New York now．
(二)用於含蓄條件句
在表示假設的虛擬語氣中，有時假設的條件並不以條件從句的形式出現，而是通過上下文或句中內在的邏輯關係，或用其他形式表達出來，這就是「含蓄條件句」。常用的有以下幾種方式：
1．介詞或介詞短語，如but for，without，in case of, under，with，in等。
But for their help，we could not get over the difficulties．
Without music，the world would be a dull place．
2．連詞，如or，otherwise，but，in case，lest，for fear that，so that等。
We took a taxi to the airport．Otherwise we should have been late．
He felt very tired yesterday，or he would have attended the party．
注意：由lest，for fear that和in case引起的從句中謂語動詞多用「should+動詞原形」，但也可以不用虛擬語氣，而用動詞的陳述語氣形式。
3. 分詞短語
United (= If they had been united), they wouldn’t have been defeated.
4.動詞不定式短語
To hear him speak English, one would think him an Englishman.
5.名詞短語和「名詞＋ and」結構
A diligent student would have worked harder.
One step further and you would be dead.
6.定語從句
Anyone who had been in your position would have done the same.
7.形容詞及其比較級
A more careful person would not have made so many mistakes.
8.獨立主格結構或由 with 引導的複合結構
All things considered, the price would be reasonable.
（三）用於混合條件句
條件從句表示的動作與主句表示的動作在時間上不一致的叫混合條件句 （錯綜時間條件句）。其主句和從句的謂語動詞應根據各自所指的時間選用適當的形式，一般從句指過去，主句指現在或將來；或從句不指某一特定時間，主句指過去；或從句用虛擬語氣，主句用陳述語氣或祈使語氣。
If you had asked him yesterday, you would know what to do now.
If the weather had been more favourable, the crops would be growing better.
（四）虛擬條件句的倒裝
在虛擬條件句中，如果從句部分含有 were, should 或 had，可將 if 省略，were, should 或 had置於從句句首，使用倒裝。
Were they here now, they could help us.
Should it rain, the crops would be saved.
Had you come earlier, you would have got the ticket.
02用於賓語從句
（一）用於 wish 後面的賓語從句
wish 後面的賓語從句可以表示與事實相反的情況，也可以表示將來不太可能實現的願望。
其賓語從句的動詞形式為：
I wish it were spring all the year round.
We wish we had arrived there two hours earlier.
I wish it would rain tomorrow.
（二）在 insist, order, command, advise, suggest, propose,demand, require, request，ask 等表示堅持」 、 「命令」 、「建議」 、「要求」等動詞後的賓語從句用虛擬語氣「（should) ＋動詞原形」。
He insisted that I (should) go with them.
He ordered that it(should) be sent back．
注意：如果insist作「堅決主張；堅持要求」講，接that從句(從句的動作為將要發生之事)時，從句常用虛擬語氣，即「(should)+動詞原形」，而表示「堅持說；堅決認為」，接that從句(從句的動作多為已發生之事)時，從句使用陳述語氣。suggest作「建議」講時其賓語從句中要用虛擬語氣，即「(should)+動詞原形」，而作「暗示」、「表明」講時則要用陳述語氣。
He insisted that we(should) accept these gifts．
He insisted that I had read his letter．
She suggested that the class meeting(should) not be held on Saturday．
What he said suggested that he was a cheat．
(三)用於would rather後面的賓語從句。從句謂語一般用過去時來表示現在或將來。在談到過去的動作時，從句謂語則用過去完成時。
I'd rather you met her at the airport tomorrow morning．
I'd rather you hadn’t told him the news that day．
03用於主語從句
「It is+形容詞／名詞／分詞+that從句」句型在表示「驚奇，不相信，惋惜，理應如此」等時，主語從句的謂語動詞用虛擬語氣，即用「should+動詞原形」。這樣的形容詞有necessary，
important，natural，strange等；分詞有desired，suggested，decided，ordered，requested，proposed等；
名詞有a pity，a shame等。should意為「應該；竟然」時，可以省去，但不可換用would。
It is necessary that he(should) be sent there at once．
It was a pity that you(should) be so careless．
It is suggested that he(should) be present．
04用於if only引起的感嘆句
if only表示「如果就好了」，它之後的感嘆句常用來表示一種不太可能實現的願望或嚮往，因而常用虛擬語氣，用過去時表示對現在情況的虛擬，用過去完成時表示對過去情況的
虛擬，用「would／should+動詞原形」表示對將來情況的虛擬。
If only she could have lived a little longer．
Look at the trouble I am in! If only I had followed his advice．
I dread the coming exams．If only I could have time to review my lessons．
05用於表語從句和同位語從句
在含有advice，idea，order，demand，plan，proposal，suggestion，request等名詞的表語從句和同位語從句中，其謂語動詞一般用虛擬語氣「(should)+動詞原形」結構。
My suggestion is that We(should) start to work at once．
What do you think of his proposal that we(should) put on a play on the English evening?
06用於as if，though引導的方式狀語從句
在as if／though引導的方式狀語從句中，有時用虛擬語氣。表示與現在事實相反，謂語動詞用一般過去時；表示與過去事實相反，用過去完成時；表示將來的可能性不大，用「would(might，could)+動詞原形」。
They treat me as though I were a stranger.
07用於定語從句
在It is (high／about) time (that)句型中，定語從句的謂語動詞用過去式或「should+動詞原形」(should不能省略，be用were表示)，意為「早該」。
It is time we left．
It is high time you should go to work．