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。

本文来自：逍遥右脑记忆 http://www.jiyifa.net/gaozhong/240151.html

相关阅读：英语高考写作备考 英语谚语集锦（十一）