21. We don’t need to do ___ extra work this evening. The day’s work was almost at ____ end now.
A. / ; an B. an; an C. the; the D. the; /
22. Although the number of competitors ___ limited, a number of our classmates ___ eager to take part in it.
A. are; are B. are; is C. is; are D. is; is
23. I'll never forget the day _________ I was born．
A.when B.that C.on which D.both A and C
