谁翻译一下伦斯菲的名言

．．．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.

这时伦部长回答记者问时讲的一段话。获得当年不知所云奖。