他不知道自己应该怎样表现。

He did not know how he ought to behave.

《牛津词典》

此时此刻，我不知道自己会作出什么决定。

At this moment in time, I don't know what my decision will be.

《牛津词典》

我开始在外面混日子，不知道自己在做些什么

I started pottering around outside, not knowing what I was doing.

《柯林斯英汉双解大词典》

Now,the problem with this is that Papias and these other people didn't really know what they were talking about.

问题是帕皮亚和其他人,根本不知道自己在说什么。

耶鲁公开课 - 新约课程节选

I chose English Literature because when I started off a university, I didn't know what it was I wanted to do.

我选英语文学是因为当我刚上大学的时候，我不知道自己到底想做什么。

为何选那门专业？ - SpeakingMax英语口语达人

I don't know. It's at this point of a possible confusion, at least a momentary, provisional confusion, that we know that the poet has identified with the sun.

我不知道，这里有一点迷惑性，至少是一种瞬间而来的迷惑，我们知道作者认为自己等同于太阳。

耶鲁公开课 - 弥尔顿课程节选