从A、B、C、D四个选项中,选出可以填入空白处的最佳选项
21.The Olympics are such great ____ that people all over the world take part in them.
A.things B.events C.matters D.affairs
22.. —What are you busy doing now?
—_____.
A.to prepare the exams I’ll take. B.preparing the exams I’ll take.
C.to prepare for the exam I’ll take D.preparing for the exams I’ll take.