单选题 John and Sue ______ computer games for hours before their parents came home from work.
  • [A] are playing
  • [B] have been playing
  • [C] played
  • [D] had been playing


【正确答案】 D
【答案解析】[解析] 考查时态。由于从句是before引出的表过去的时间状语，因此主句也要用过去时态；而主句中又有一个表示时间段的状语for hours，故主句还要用完成时态。[D]项为过去完成进行时，强调在过去某一时间段内一直做某事，符合题目要求。