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.
3. wish后宾语从句中的谓语构成
动词wish后的宾语从句表示未实现的或不可能实现的愿望，其宾语从句中的谓语动词要用虚拟语气，有以下三种构成形式。
1) 表示现在不可能实现的愿望，宾语从句中的谓语动词用一般过去时。(be的过去式为were)。
I wish I had enough money to buy a car.
I wish I were as young and energetic as you.
2) 表示过去未能实现的愿望，宾语从句中的谓语动词用过去完成时(had +过去分词)或“would / could + have +过去分词 ”。
I wish I hadn’t made such a mistake.
I wish I could have done it better.
3) 表示将来不可能实现的愿望，宾语从句中的谓语动词用“would / should (could, might) +动词原形”。
I wish I would not get old.
I wish I could travel around the world one day.