recognize 、realize 、understand 、know 它们的意思里面都有认识 理解 意识 知道等差不多的意思 。

recognize:认出

realize:认识到，意识到

understand:明白

know：知道，认识

在句子中理解：

我知道答案，但我不明白，而且我没意识到我是错的：i knew the answer, but i didn't understand, and i didn't realize i was wrong.

我认识你，但我刚才没认出你来：i know you. but i didn't recognize you.