ascertain
动词 ascertain:
establish after a calculation, investigation, experiment, survey, or study
be careful or certain to do something; make certain of something
同义词:see, check, insure, see to it, ensure, control, assure
find out, learn, or determine with certainty, usually by making an inquiry or other effort
同义词:determine, check, find out, see, watch, learn
learn or discover with certainty