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.