但马克知道，自己必须小心行事。

But Mark knew that he should proceed with caution.

youdao

这次爆炸被归咎于一起事故但是马克知道，内情远非如此。

The explosion is blamed on an accident but Mark knows otherwise.

youdao

我知道马克迟到是出了名的。

I'm aware of Mark's reputation for being late.

《牛津词典》

He mentioned the Nicomachean Ethics which I have never read I don't know what that is.

他提到了《尼各马克伦理学》,一本我从没读过的书，我不知道那本书是讲什么的。

耶鲁公开课 - 金融市场课程节选