单选题 They ______ on the program for almost one week before I joined them.
  • [A] had been working
  • [B] bad worked
  • [C] have been working
  • [D] have worked


【正确答案】 A
【答案解析】该题考查动词时态的用法。根据句意应该选过去完成进行时，表示work on这个动作在 joined以前发牛，而且．我加入以后还在继续，故用过去完成进行时。答案为A。