我知道你的名字，但不知道你的姓氏。

I know your first name, but I don't know your family name.

youdao

他们很饿，但不知道怎么弄到足够的吃的，而不惹出闲话。

They're that hungry they don't know how to get enough to eat without makin' talk.

youdao

我知道你的姓，但不知道你的名字。

I want to know your first name.

youdao

And I don't know why, but since time immemorial that is the way computer scientists have drawn trees.

叶子是在最下面的，我不知道为什么,但从记事以来他们就是这么画树的,这也许就是为什么我们。

麻省理工公开课 - 计算机科学及编程导论课程节选

But for me, I like to look at something and just say, "I like this. I don't really know why though."

但对我来说，我喜欢看着某个东西，然后说，“我喜欢这个。但我也不知道为什么。”

关于现代美术 - SpeakingMax英语口语达人

We've had a great deal to do with it, but of course we still haven't the slightest idea what it is.

我们花了很大的功夫来接解决这个问题，但我们仍然一点都不知道语言是什么。

耶鲁公开课 - 文学理论导论课程节选