混合条件句
 
　 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).
 
 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 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.

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.