二、单项选择（共15题，每题1分，计15分）
从A、B、C、D四个选项中选出一个可以填入句中空白处的最佳答案。
21. — Mum, why can’t I have ___▲__ new bike?
— Dear, you know, ___▲___ money doesn’t grow on trees.
A. the; the B. a; / C. a; the D. /; the
22. My little cousin is not old enough to look after ___▲____ when his parents are away.
A. he B. his C. him D. himself
23. The students were happy that they would have a ____▲___winter holiday.
A. three-weeks B. three week’s C. three-week D. three-week’s
