to insist on getting to the bottom of a matter; to be inquisitive. This form is a pun using a character meaning crack to replace a word meaning ask, suggesting that when a clay pot is broken, the crack goes all the way to the base

To insist on getting a detailed answer or finding out the root cause of something. This idiom is a pun: a broken clay pot has a crack that goes to the bottom, and the word for crack [[璺|璺|wen4]] sounds like the word for ask [[问|問|wen4]].