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. As is known to all , great scientific achievements may have positive effect on our life as well as society.
A. /；a B. the；the C. the；/ D /，/
22. we gave him something to eat, he would save it up for his little sister.
A. Whatever B. However C. Whenever D. Whichever
