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. A _______to this problem is expected to be found before long.
A. result B. response C. settlement D. solution
22. The new procedure is _______ the old one.
A. great improvement to B. great improvements for
C. a great improvement on D. the great improvement in
