The story is very interesting, so most of us like it.
—Always look around________you cross the street,David. —OK.I know,Mum. A.until B.before C.unless
The thieves ran away at once when the burglar alarm(防盗报警器)________.
—Did you see Mr Smith when you were in France? —No.When I________France,he________to China.
He told us that he________the letters in the morning.
By nine o’clock yesterday evening,we________our work.