从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
21. --- Can I look at the menu for a few more minutes before I order?
--- Of course. _______, Sir.
A. Make yourself at home B. At your service
C. Take your time D. It doesn’t matter
22. What lesson China can draw from ____ financial crisis (金融危机) in the United States has become _____ hot topic in Beijing..
A. the; a B. /; the C. a; a D. the; /
