Everything was placed exactly ________ it used to be before she left the laboratory.
A．why B．when
C．where D．though
________ I'm mistaken, I've seen that tall man at a party before.
A．If B．As
C．Unless D．When
Beijing is ranked first in terms of traffic jams and expenses for culture ________ Guangzhou is more open to peasant workers than Beijing and Shanghai.
A．when B．since
C．while D．because
________ he stops driving himself like this, he'll have a breakdown.
A．Until B．Once
C．Since D．Unless
________ my teacher didn't tell me directly, I still felt that I didn't live up to her expectation.
A．When B．Since
C．As D．While
I was wondering what to do with my car which won't start ________ a kind man offered to help.
A．while B．and
C．so D．when
