Weknowthroughpainfulexperiencethatfreedomisnevergivenbytheoppressor;itmustbe_____
Weknowthroughpainfulexperiencethatfreedomisnevergivenbytheoppressor;itmustbe____________bytheoppressed
AdemandedBrequiredCcommandedDrequested
为什么选A?并比较分析一下这四个词.