find 发现,找到 强调找的结果,后可以接名词、复合结构或that从句 Have you found the book you left on the bus? 你找到你落在公车上的书了吗? find out 找出,查明 指通过观察、探索而发现事实的真相、真情;调查找出原因,或发现秘密、错误等。后一般接名词、代词或从句 Have you found out why he was late? 你弄清了他为什么迟到吗? know of 听说过,知道 I don't know Mr Smith but I know of him. 我不认识史密斯先生,但是我听说过他。