第二部分：词汇知识运用（共两节，满分30分）
第一节：多项选择（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.________ she decided what to do, none of us can stop her.
A. Once B. Unless C. Before D. Since
22.Hurry! The train __________. You know it _________at 8:30 am.
A. leaves; leaves B. is leaving; leaves
C. leaves; is leaving D. is leaving; is leaving
