第二部分：英语知识运用（共两节，满分45分）
第一节：单项填空（共15小题；每小题1分，满分15分）
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. The International Red Cross is_______ non-profit organization that cares for the wounded, sick and homeless in wartime, and victims of _______ natural disasters.
A. the; the B. a; the C. the; 不填 D. a; 不填
22．While building a tunnel through the mountain, ________ .
A. an underground lake was discovered B. there was an underground lake discovered
C. a lake was discovered underground D. the workers discovered an underground lake
