第一节 单项填空（共10小题；每小题1分，满分10分。）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
20. I want to have a short talk with you. Could you please spare a few minutes ________?
A. if possible B. if necessary C. if important D. if worthwhile
22. The Browns held _____ they called "family day" once each year.
A. that B. what C. which D. when
23.In some parts of London, missing a bus means __________ for another hour.
