Never believe anything ______ any other person has believed it.
---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.
__________ they will not come to join us, we have to change our plan.
That is __________ the problem lies.