二、选择填空(共15小题，每小题1分，满分15分)
从A、B、C、D四个选项中，选出可以填人空白处的最佳选项。
21. -- John, it's 10 p.m. It's time to go to bed now.
-- OK, ______, Mum!
A. good morning B. good afternoon C. good evening D. good night
22. Look, Simon, ______ Walkman that I bought last year isn't working properly.
A. a B. an C. the D. 不填
23. ______ police officers in the UK carry guns, but most of them don't.
A. No B. Some C. Many D. All
