Know something inside out 對某事瞭如指掌

表達 「know something inside out」 的意思是 「對某件事情、某個科目或主題瞭如指掌、洞悉透徹」。

例句

Don’t worry! You’ll be fine in tomorrow’s exam. You know the book inside out by now!
別擔心！明天的考試你一定會考好的。你現在對這本書已經瞭如指掌了！

If you ever have any questions about the new IT system, ask Polly. She helped build it, so she knows it inside out.
如果你對新的信息技術系統有任何疑問，就去問波莉吧。這個系統是她幫忙建立的，所以她對整個系統瞭如指掌。

My grandad was a chess fanatic. You could ask him anything – he knew the game inside out.
我祖父曾是個國際象棋迷。你可以問他任何問題，他對這個遊戲瞭如指掌。