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. This is Mrs. Brown, ________ teacher from Australia working at ________ university in our country.
A. a; a B. a; an C. the; an D. a; /
22. -- Personally, making a joyful face not only helps us make friends but also makes us feel better.
-- ________.
A. I’d love to B. It’s up to you
C. I’m with you on that D. It’s my pleasure
