I don't know how bad the injury is, because I have never had one like this before.

我不知道伤势有多重，因为我以前从未受过这样的伤。

《柯林斯英汉双解大词典》

—Michael was late for Mr. Smith's chemistry class this morning. —How come? As far as I know, he never came late to class.

——今天上午迈克尔在史密斯老师的化学课上迟到了。 ——怎么会呢？据我所知，他上课从不迟到。

youdao

To this day I do not know why these "spirits" are here doing this to me and I have a feeling that I will never know.

直到今天，我还不明白为什么“幽灵”会在家里如此对我。我觉得也许我将永远不会知道。

youdao

"The court of appeals is where policy is made, and I know this is on tape and I should never say that because we don't make law.I know,I know.

VOA: special.2009.05.30

If I had not done this, I would never know what I did not know.

FORBES: To Continue Growing, Quit The Big Job

Before I start to write, I have to know one thing: So, I guess Beyonce was never actually part of this, eh?

FORBES: The Action Movie Blog Post

Do you know, I never thought I would write this one.

BBC: Full text: Burrell interview