盘根问梢pán gēn wèn shāo

cross-examiner make exhaustive inquir.es about
❍ 每住到一个村庄里，半夜三更里常常碰到查户口的，一，翻箱倒箧。(杨植霖《王若飞在狱中》 14) Travellers who happened to stop over in a village were often wakened in the dead of night by Kuomintang soldiers who cross-examined them and ransacked their trunks and suitcases.
❍ 甚至连马克思，恩格斯、列宁、斯大林，都要～，问他们现在都活着没有，会不会说中国话，……(杨植霖《王若飞在狱中》70) He even made exhaustive inquiries about Marx,Engels,Lenin and Stalin—whether they were still living,whether they could speak the Chinese language.