单选题 The passengers and the suitcases ______ were still waiting had to be transferred to another plane.
A. which B. that C. who D. whom

【正确答案】 B

【答案解析】仍在等待的乘客和行李只得改乘另一架飞机。此句考查定语从句中的关系代词。此处的关系代词需要指代主句中的the passengers and the suitcases，既指人又指物，所以只能用that。