know something inside out
熟悉某事物至極，了解得透徹
口語·表達極度熟悉
英文釋義
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.
典故來源
與'know something inside and out'同源，強調對細節的徹底掌握。