to find out whether sth is definitely true :
I think there's a bus at 8 but you'd better call to make certain.
to find out whether sth is definitely true :
I think there's a bus at 8 but you'd better call to make certain.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005