20. Between the two generations, it is often not their age, _________ their education ______　 causes misunderstanding.

　 A. like; which　　　　 B. as ; that　　　　 C. or; what　　　　　 D. but ; that

19. ---Depend on it, I will give you what help I can.

---___________________ .

A . I can never thank you enough.　　 B. It’s all part of the service.

C. Oh, nothing doing　 　　　　　　　 D. Suit yourself