从A、B、C、D四个选项中，选出可填入空白处的最佳选项，并在答题纸上将该项涂黑。
21．As is widely accepted, _______ students should have ______ easy access to labs, libraries and other facilities at school.
A. /; an B. the; an C. the; / D. /; /
22．—Better get down to your work, Tom.
—_________.
A. It’s my pleasure B. Don’t mention it
C. Mind your own business D. You’re welcome
23．—You look so young. Haven’t you graduated from university?
