从每题所给的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. I wonder we haven’t received her invitations yet. Her wedding is only two days away.
A. how B. why C. that D. when
22. The computer programs are a puzzle to me. The more I think of them, the more questions I think of .
A. ask B. asked C. being asked D. to ask
