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. He couldn’t remember when he first listened to U.S. President Obama’s speech, but he was sure it was _____ Monday because everybody was at ______ work.
A. /, the B. the, / C. a, / D. /, a
22. We ______ to move but are still considering which place to go to.
A. are deciding B. decided C. have decided D. had decided
