động từ
to clear, agree, consent
to open; to allow , traffic through
to go over or through, to cross, open
to be fluent or conversant, understand
to clear off, to unchock, to unclog, clear
to master, be master or be conversant with
to ream out (tube, pipe), clean (out), cleanse throughly
understand the present, have a wide knowledge of the past/leaned, well-informed, erudite