know-nothing

He closed up when he found he knew practically nothing about the subject under discussion.

当他发现自己对所讨论的问题实际上一无所知时, 就口了。

This might seem very perplexing to those who know nothing about it.

这对那些对它一无所知的来说可能显得很难理解。

However, we can know nothing through this process about the "numina" (inward realities) of nature.

但是，在这一过程中，我们对自然界的“numina”（内在现实）依然毫无所知。

I know nothing at all about the recent happenings there.

对那里近来发生的事我一点儿也知道。

I hasten to add that I knew nothing of the fraud at the time.

我忙迭地补充说，我当时对那个骗局一无所知。

I know nothing but Wikipedia is a cyclopedia which is easy to use,free and grow continuously.

我只知道维基是一个非常好用的，免费的，断成长的百科全书。

He knows nothing of unprofessional matters.

与专业无关的事, 他什么也知道。