在英语四级考试中单独考察的题几乎没有，但是语法知识点却贯穿整张试卷，下面是小编为大家整理的知识，希望可以为大家带来帮助，一起来学习一下吧。
　　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.