inside out
1．upside down 翻过来；倒过去；里在外
The wind blew Mary's umbrella inside out．风把玛丽的伞吹得翻过来。
He was wearing his coat inside out．他把衣服反穿着。
I turned my trouser pockets inside out but could not find the piece of paper with the address．我把裤子口袋翻过来也没有找到留有地址的那张条子。
2．perfectly；completely 完全地；彻底地
He knew his trade inside out．他对他的业务了如指掌。
Since he knows the problem inside out，he has more say on it that I do．他对这个问题了解得很清楚，因此，他比我更有发言权。