(Had I known)you were coming today,I'd have met you at the r

(Had I known)you were coming today,I'd have met you at the railway station.
一种特殊的虚拟语气表达方法
原句:If I had knownyou were coming today,I'd have met you at the railway station.
if 省略 had 提前从而达到加强语气的目的.
If I had known the secret,I would have told you.
Had I known the secret,I would have told you.
If it were to rain tomorrow,I would stay at home.
Were it to rain tomorrow,I would stay at home.