[英文文法] If 引導的副詞子句，可將were、should、had提至主詞前

在書上看到第二次了，感覺滿重要的。

If引導的副詞子句中，若有were、should或過去完成式助動詞 had出現時，都可以將were、should、had置於主詞之前，省略原有的 if。

例如:
If it were not for you, I wouldn't do it.
Were it not for you, I wouldn't do it.
若不是因為你，我才不會去做呢。

If Paul were here, I would tell him the truth.
Were Paul here, I would tell him the truth.
如果Paul在這裡，我將會告訴他真相。


If I had learned about his situation yesterday, I would helped him.
Had I learned about his situation yesterday, I would helped him
如果我昨天就了解她的情況，就會幫助他了。

If I had seen him yesterday, I would have told him the truth.
Had I seen him yesterday, I would have told him the truth.
如果我昨天有看到他，我將會告訴他實情。

If you should do that again, I would punish you.
Should you do that again, I would punish you.
若你再犯，我將會懲罰你。

補充說明
if 搭配 should 表示 "萬一"
If it should rain tomorrow, the picnic will be cancelled.
(萬一明天下雨，野餐會取消)