see to it, find out, assure, control, see, ensure, insure, evidence, learn, determine, more...

disprove, doubt, question, refute, deny

find out, discover, uncover, reveal, unearth, more...

french, present, first, dyspeptic, dark, better, spanish

be sure,   to determine,   be sure of,   know for sure,   to be certain,   know for certain,   to be sure of,   know with certainty,   become certain,   to know the truth