Right, having done that, we can certainly get to more complicated things, so for example, suppose I look at that expression.

好，说完了这一点，我们就可以讲些复杂些的话题了，例如，假设我看到了这个表达式。

麻省理工公开课 - 计算机科学及编程导论课程节选

to express a lack of complete knowledge about the multitude of subjects.

它可以用来表达你对一些话题并不完全了解。

I don't know 课堂 - SpeakingMax英语口语达人

or perhaps an uncommitted response in a variety of subjects.

又可以在各种话题中表达一种中立的回答。

I don't know 课堂 - SpeakingMax英语口语达人