归根究底的

last-minute

归的英语翻译：

go back to; return; turn over to

根究的英语翻译：

probe into

底的英语翻译：

a copy kept as a record; base; bottom; end; fundus; the truth of a matter
【医】 base; basement; bases; basi-; basio-; basis; batho-; bathy-; fimdi
floor; fundus; pavimentum; solum