第一节：单项填空（共15小题；每小题1分，满分15分）
21. –Jack bought a new mobile phone the other day.
--______? That’s his third one in just one month.
A. Had he B. Did he C. Does he D. Has he
22. It's true that the old road is less direct and a bit longer．We won't take the new one, ________, because we don't feel as safe on it.
A. when B. therefore C. while D. though
