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, 并在答题卡上将该项涂黑。
21. According to _______ announcement by Guangzhou Price Bureau, _______ the new measures which have been taken recently are expected to cut the operation costs of each taxi driver by 1280 yuan.
A. the; / B. an; the C. /; the D. an; /
22. It was four o’clock in the afternoon _______ they got to the station.
A. that B. since C. when D. until
23. _______ around the Water Cube, we were then taken to see the Bird’s Nest for the 2008 Olympic Games.
A. Having shown B. To be shown C. Having been shown D. To show
24. Considering your salary, you should _______ at least 100 dollars a week.
A. put up B. put forward C. put aside D. put out
