If you want to know whether you are fit to learn history and geography, you’d better _________ your head teacher.
Don’t have the lights ______ all day long. It is a waste of electricity.
Either you or the headmaster ______ the prizes to the gifted students.
The 2010 Shanghai World Expo is well worth ______.
I am interested in traveling. It is ______ but ______.
The windows haven’t cleaned for a long time. They need ______.