I cannot know it positively, in other words; I can only know it negatively.

换言之，我不能从正面了解它，只能从反面来了解。

youdao

I do not know what to do with the information if I cannot pass it on.

如果无法传送出去，我不知道该拿这情报怎么办。

《柯林斯英汉双解大词典》

I just cannot resist chocolate, even though I know eating too much of it will do harm to my teeth.

尽管我明白吃太多巧克力对牙齿不好，但我还是抵挡不住巧克力的诱惑。

youdao

Sergeant Perry Osburn put it this way: "We cannot let this make us afraid, you know what I'm saying?

VOA: special.2009.11.14

He says--and here's that Yeatsian word "all" again--he says: When I try to put all into a phrase I say, "Man can embody truth but he cannot know it."

他说，又是他涵盖一切的词：,当我想用一句话概括时，我说，人可以表现他不理解的真理“

耶鲁公开课 - 现代诗歌课程节选

You cannot say, "I never heard of it. I don't know where it came from."

你就不能再说,"我从没听说过,我不知道它是怎么来的"

耶鲁公开课 - 基础物理课程节选

Let's touch on Easter for a moment, how do you feel and how do you respond to people who say I believe in God, I believe in Christ, I'm a Christian but I cannot accept the Resurrection as a historical fact when I know you regard it as the heartbeat of Christianity?

BBC: News Online

But I have said this before, and I know, Iowa, you heard me say it: He cannot do this alone.

WHITEHOUSE: Remarks by the First Lady at a Campaign Event

"I know lots of other soldiers have nothing good to say about the rehabilitation process but I cannot fault it, " he said.

BBC: News, Surrey