Listen! ________ is knocking on the door. Go and see who it is.
—Sorry,Mr Green.I________my English book at home. —That’s OK,but don’t________next time.
Miltie________a picture when Mr.Green came in.
—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.