adverb, punctuation · to not know or be unaware of a fact or situation

我不知这件事的真相。

adverb, idiom · without realizing; in an unconscious or unintentional manner

两人聊得投机，不知时间已过半夜。

adverb · to not acknowledge, feel, or give in to (defeat, fatigue, hardship, etc.)

他为了完成实验，整整三天不知疲倦地工作。