________Beijing you see today is quite ________ different city from what it used to be.
We were struck by the limited use __________ their natural resources.
Cook was a strict but good captain, __________ usually took care of the sailors on his ship.
---How long do you think it will be __________ China sends a manned spaceship to the moon?--- Perhaps two or three years.
You’d better take something to read when you go to see the doctor __________ you have to wait.
Tom is one of the boys who __________ on time.