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。
21. Once __________sport has become less popular, it has to make __________way for new sport which are more popular to enter into the Olympics.
A. the；a B. a；／ C. ／；the D. the；／
22. A new __________to teaching English, is being used here, and it has proven to be very helpful to the students.
A. way B. system C. approach D. method
23. His little daughter was so __________that he could easily pick her out in the crowd.
A. personal B. unique C. ordinary D. pure
24. The function of an advertisement is that it can __________customers to buy the kinds of goods.
