get to the bottom of the matter; investigate into an affair thoroughly;make a thorough inquiry into sth; inquire into the utmost details
? 我感到這樣事情里面有問題，我建議～。I’ve smelt a rat in the matter. I suggest that we make a thorough inquiry into it.
窮源竟委qiónɡ yuán jìnɡ wěi
窮、竟：根究、追究；源：指水流的發(fā)源；委：末尾。比喻深入探究事物的始末。make a thorough, inquiry into sth., get to the bottom of the matter, go behind sth.