语法结构
1.if结构（非真实条件句——表示的是假设的或实际可能性不大的情况）
与..事实相反 If从句 主句
过去 Had done Would* have done
现在 Were/did Would* do
将来 Should do/were/were to do Would* do
例句：If there hadn’t been much rain in spring, we would have had a good harvest now. [过去]
If he smoked less, his cough might be well soon. [现在]
If the lecturer should be late, you would have to make a speech first. [将来]
备注：
（1）上表中’*’，would都可转换为should、could、might。
（2) 如果为时间错综句的话，左右两栏可互相搭配，排列组合。
例句：
He would still be alive today if he hadn’t taken that drug.
[与现在事实相反] [与过去事实相反]
(3) if可转换为其他形式
例句：Without your advice, our meeting wouldn’t have been so successfully. [过去]
（=>可转换为：If there hadn’t been your advice, we …）
Your notes are almost illegible (难以辨认的). Notes typed out would be a lot easier to read. [将来]
(=> 可转换为：If the notes had been typed out, it would be a lot easier to read.)
I should have gone to see Dr. Smith and he might have cured me of the disease.[过去]
(=> 可转换为：If he have gone to see Dr. Smith, he ..)
2、wish结构
与..事实相反
过去 Had done
现在 Were/did
将来 Would
备注：可转换为其他形式。
例句：He talks as if (好像) he had done all the work himself. [过去]
I wish I were a bird.
I wish he handn' done that.
I wish I would be rich in the future.
3、should结构
从句中用“should + 动词原形”构成。而且should可以省去。用于此结构的动词有：advise, direct, agree, ask, demand, decide, desire, insist, order, prefer, propose, request, suggest,intend等。
例句：The teacher suggest he (should) read English aloud.
注意：当insist表示“坚持认为”、suggest表示“表明，显示”时，不用虚拟语气。
例句：The look on his face suggested that he was quite satisfied with what I had done for him.
He insisted that he was honest.
4、would rather ＋从句
在这种结构中，从句的谓语动词用过去形式表示虚拟。
例句：I would rather you did this instead of me.
5、主语从句中的虚拟语气
1）It be + 形容词 + that ．．．（should）．．．
用于该句型的形容词是：necessary, good, important, right, wrong, better, natural, proper, funny,
strange, surprising ．
一些名词也可以用于 在该结构中。如：a pity， no wonder．．．．
2）It be + 过去分词 + that ．．．（should）．．．．
用于该结构中的过去分词是表示“建议、请求、命令”等词的过去分词。如：desired， suggested， requested，
ordered， proposed等。
3）It is time（about time， high time）that ．．．（过去式动词形式或should＋动词原形）．．．．
It is high time I went home now. = It is high time I should go home now.
6、表语从句、同位语从句中的虚拟语气
在suggestion， proposal， order， plan， idea， advice， decision等需要有内涵的名词后面的表语从句、同
位语从句中，要使用虚拟语气。其谓语动词应用：should＋原形动词。另外连接从句的that不能省
略。
例：My suggestion is that we should go there at once.
What do you think of his proposal that we should put on a play at the English evening?
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