16. I have studied in this school _______three years ago.
A. since B. for C. before D. after
17. There _______some tall trees here before, but there aren't now.
A. used to B. used to have C. used to be D. was
18. Don't get off the bus _______it has stopped.
A. after B. when C. if D. until
19. _______great fun it is! And _______good time they are having!
A. What a; what B. What; what a C. How a; how D. How; how a
20. When Eddie is_______, he sometimes feels_______.
A. alone; alone B. alone; lonely C. lonely; lonely D. lonely; alone
21. -_______a year does your school have a sports meeting?