How to write 归根到底归根到底

surname Gui

root; basis; classifier for long slender objects, e.g. cigarettes, guitar strings; radical (chemistry)

to reach; to arrive; to leave for; to go to; to (a place); until (a time); up to (a point); (verb complement indicating arriving at a place or reaching a point); considerate; thoughtful; thorough

(equivalent to 的 as possessive particle)