从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21.In order to help disabled to lead a normal life and enjoy fruits of social
A. the；不填 B. the；the C. a；the D. 不填；the
22.－ Where was it Mark Twain spent much of his childhood?
－ Along the Mississippi river.
A. that B. which C. when D.不填
