I was about to leave the office ______ an unexpected visitor came.A. while B. as C when D. before
According to the factory safety rules, all accidents _____ be reported to the safety officer.
John seemed puzzled about _____ the question meant.
Everyone tells me I’m a good speaker, _____ I really don’t like speaking in public.
—You've got a cold, not the H7N9! Everything will turn out OK. —______! I have been worrying about it for days.
Mike apologized for _______ to inform her of the change in the working plan.