This is the one thing I cannot know.
这是一件我没法知道的事情。
There are things I cannot know. But there are also things that I do know.
有一些事情，我可能无法知道；但也有一些事情，我的确知道。
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。
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。
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