Had I known it earlier, I would have helped him.

如果我早知道这件事，我就会帮助他。

youdao

Had I known it, I would have told you the bad news.

如果我知道的话，就早告诉你这个坏消息了。

youdao

It might have saved me some trouble had I known the schedule.

如果我知道日程安排的话，就不会那么麻烦了。

youdao

"I've known other actresses who had it." "I had a friend who had a little bump on her nose.

VOA: standard.2010.07.22

And I had known it, but I was in an encounter group in New York with a bunch of people, some of whom were friends.

NPR: Judy Collins, From Both Sides Now

That I misremembered that a girl in college had canceled our date after seeing my wheelchair a first time (when in fact she had long known that I used it) reminded me that I had long seen the shadow of disability where it was not present.

CNN: Is our suffering God's will?

If I had known the restaurant's name, I would have known it was closed for lunch on Mondays, when I went.

WSJ: Help Wanted: Moonlighters for Mobile Apps