求一段英语短语 忘了是谁讲的了 反正里面都是i know you know known什么的 很多know和known

The Unknown
As we know,
There are known knowns.
There are things we know we know.
We also know
There are known unknowns.
That is to say
We know there are some things
We do not know.
But there are also unknown unknowns,
The ones we don't know
We don't know.
是这个么?是一首诗 拉姆斯菲尔德（美 前国防部长） 写的
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回忆录取名《已知与未知》,源自拉姆斯菲尔德那段堪称经典的“绕口令”：
“据我们所知,有‘已知的已知’,有些事,我们知道我们知道；我们也知道,有 ‘已知的未知’,也就是说,有些事,我们现在知道我们不知道.但是,同样存在‘未知的未知’——有些事,我们不知道我们不知道.”
”