这位父亲说，他小儿子还在楼上，但他不知道具体位置。

The father said his younger child was still on the upper level of the house but he didn't know where.

youdao

伽利略所提出的观点是，太阳黑子确实是太阳的某一个特征，但他不知道是什么特征。

What Galileo proposed was that sunspots were indeed a feature of the Sun, but he didn't know what kind of feature.

youdao

但他不知道社区意味着什么？

He doesn't know what community means?

youdao

And even though he could figure out that this wasn't possible, he still used this as a starting point, and what he did know was that these energy levels that were within hydrogen atom were quantized.

这是不可能的了,但他还是以此为出发点，他知道，氢原子的这些能级,是量子化的,而且他也知道，我们上节课所看到现象。

麻省理工公开课 - 化学原理课程节选

But I don't really know 'cause he didn't have the Internet. See?

但我不知道具体的结果，因为他不能使用网络。明白了吗？

理想是当密码专家 - SpeakingMax英语口语达人

Oh yeah, I know Hanson, but if I didn't know him, I wouldn't know any farmers.

好吧,我知道汉森,但我不认识他,我一个农民都不认识

耶鲁公开课 - 古希腊历史简介课程节选