21. There are more opportunities for disabled people to make______ contribution to______ society.
A. a, the B. a, / C. /, the D. the, a
22. She may have missed the train, ______ she won’t arrive for another hour.
A. in which case B. in the case C. in any case D. in that case
23. Don’t respond to any e-mails ______personal information, no matter ______ official they are.
A. requested, how B. requesting, how C. requesting, what D. requested, what
