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. Besides being short, a good dialogue must be ______ in such a way that the speakers’ parts are balanced.
A. updated B. constructed C. demonstrated D. valued
22. In time of war, different parties tend to ______ their political differences to fight against foreign invaders shoulder to shoulder.
A. pick up B. relate to C. set aside D. give away
