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择。并在答题卡上将该项涂黑。
21. I cannot support a policy of which I have never ___________.
A. accomplished B. approved C. applied D. abandoned
22.Experts warn that global warming will cause dramatic climate changes including more________ floods , heat waves and droughts.
A. frequent B. usual C. ordinary D. common
