know something inside out
熟悉某事物至极，了解得透彻
口语·表达极度熟悉
英文释义
To be very familiar with something, to know it very well.
例句
He knows the city inside out, so he can give you the best directions.
典故来源
与'know something inside and out'同源，强调对细节的彻底掌握。