从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
16. The customer praised the manager, who, ______ praised his staff.
A. at random B. by chance C. in turn D. on occasion
17. ---I went to the ticket office, but the tickets had been sold out already.
---You could have ______ yourself an unnecessary trip by phoning in advance.
A. prevented B. made C. enjoyed D. spared
18. --- Frank, you need to refresh yourself with a cup of coffee.
---Yeah, I went to bed very late last night, ______, early this morning.
A. rather than B. what’s more C. or rather D. what’s worse
19. ---What do you think of teaching, Bob?
---I find it fun and challenging. It is a job ______ you are doing something serious but interesting.
A. where B. which C. when D. that
20. The committee has rejected our proposal. ______, they have brought forward an alternative plan.
A. Therefore B. However C. Instead D. Besides
21. It is illegal for a public official to ask people for gifts or money ______ favor to them.
A. in preference to B. in place C. in agreement with D. in exchange for
22. His idea of having weekly family meals together, which seemed difficult at first, has ______ many
good changes in their lives.
A. got through B. resulted from C. turned into D. brought about
