单选题 The police have asked for the ______ of the public in tracing the whereabouts of the missing child.
  • A. award
  • B. so-operation
  • C. position
  • D. helpfulness
【正确答案】 B
【答案解析】[解析] 各项的意思为：award奖品；cooperation合作；position位置，阵地；helpfulness有益，有用。