虚拟语气的使用范围及判断
一虚拟语气表示一种不能实现的假设。该语法主要用于if 条件状语从句。也可用于主语从句、表语从句、宾语从句等。
二 if 条件状语从句中虚拟语气的判断
If 条件状语从句有真实条件句和非真实条件句。假设条件可以实现的句子为真实条件句（如在阴天说if it rains, we would not go out），反之为非真实条件句，要用虚拟语气。
三假设条件一般为：
1） 与过去事实相反，从句谓语动词用过去完成时，主句动词为情态动词＋完成时态。
e.g. If I had come here yesterday, I would have seen him.
2） 与现在事实相反，从句谓语动词用一般过去时，主句动词为情态动词＋动词原形。
e.g. If I were a teacher, I would be strict with my students.
3） 与将来事实可能相反，从句谓语动词用过去将来时，主句动词为情态动词＋动词原形。
e.g. If it should snow tomorrow, they couldn’t go out.
主句谓语动词为情态动词（should, would, could）＋和相应的从句一致的动词形式。
四 if 条件句中如果有were, should, had, 可以省去if, 并使用倒装句序。
宾语从句中的虚拟语气
一 wish后面宾语从句中的虚拟语气：根据从句的意义来判断：
1．与现在和将来相反的事实，从句谓语动词用过去时态；
e.g. I wish I were a bird.
2．与过去相反的事实，从句谓语动词用过去完成时态。
e.g. I wished he hadn’t done that.
二表示“要求、建议、命令”等动词后面的宾语从句中的虚拟语气
从句用“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等。
e.g. I insisted that he (should) go with them.
He suggest that a meeting (should) be held to discuss the matter.
He demanded that I (should) help him.
注意：当insist 表示“坚持认为”、suggest表示“表明，显示”时，不用虚拟语气。
e.g. He insisted that he was honest.
The look on his face suggested that he was quite satisfied with what I had done for him.
三 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。
e.g. I would rather you did this instead of me.
主语从句中的虚拟语气
一 It be + 形容词+ that…. (should)….
用于该句型的形容词有： necessary, good, important, right, wrong, better, natural, proper, funny, strange, surprising, etc.
e.g. It is necessary that we should get everything ready by the end of the week.
It’s natural that he should feel hurt.
一些名词也可用于此结构中，如 a pity, no wonder, …..
二 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。
e.g. It is desired that the building of the house be completed next month.
三 It is time (about time/ high time) that…
虚拟语气 虚拟条件句的倒装
虚拟条件句的从句部分含有were， should， 或had时， 可省略if，再把were， should或had 移到从句的句首，实行倒装。例如：
Were they here now， they could help us. =If they were here now， they could help us.他们现在在的话，就会帮助我们了。
Had you come earlier， you would have met him. =If you had come earlier， you would have met him.你来得早一点，就碰到他了。
Should it rain， the crops would be saved. =Were it to rain， the crops would be saved.假如下雨，庄稼就有救了。
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。例如：
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 I B. 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.
We are all for your proposal that the discussion should be put off(推迟)
六、名词从句虚拟语气
(1) ask, advise, beg, command, demand, decide, desire, insist, order, prefer, propose, require, recommend, request, suggest, urge等表示命令、要求、建议等含义的动词后的宾语从句中，谓语动词用(should)+动词原形, eg. I suggest / suggested that we (should) go tomorrow.名词从句虚拟语气
(2) It is +(形容词/过去分词/特定名词)+that的从句中，形容词主要是表示令人吃惊的、重要的、必要的、关键的等词汇。形容词：astonishing, amazing, advisable,
appropriate, crucial, desirable, essential, important, imperative, keen, necessary, natural, normal, odd, proper, preferable, strange, sorry, shocked, surprising, urgent, unusual, vital等。名词从句虚拟语气
(3) 过去分词：decided, desired, demanded, ordered, requested, recommended, suggested等;名词：advice, decision, desire, demand, suggestion, motion, pray, resolution, wish, preference, proposal, recommendation, requirement, idea, order等
