insist on getting to the bottom of the matter

dǎ pò shā guō wèn dào dǐ ㄉㄚˇ ㄆㄛˋ ㄕㄚ ㄍㄨㄛ ㄨㄣˋ ㄉㄠˋ ㄉㄧˇ