请认真阅读下面各题, 从题中所给的A、B、C、D四个选项中, 选出最佳选项, 并在答题纸上将该项涂黑。
21. The World Expo is like ________ great stage for people to contact ________ rest of the world.
A. a; 不填 B. the; 不填 C. a; the D. the; the
22. In terms of the knowledge of science, few students in our class can really ________ Christopher.
A. suit B. compare C. win D. match
23. Shortly after the big fire in Shanghai on November 15, the police took immediate action to ________
the cause of the fire.
A. look up B. look on C. look into D. look out
24. There ________ a trend that 3D films will become more popular ever since the film Avatar was shown.
