2. 虚拟条件句连接词if的省略
　　如果虚拟条件句的从句中含有were, had, should, could等词时，可以省略连接词if，但这时必须把were, had, should, could等词移到主语前面，形成倒装。这种句型主要用于书面形式。

　　Were I to do the job, I would finish doing it within two weeks.
　　Had it not been for his help, we couldn’t have arrived there on time.
　　Should it rain tomorrow, I would stay at home.