11.【2019 •甘肃省兰州市】Peter with his classmates ____ for the bus when the earthquake happened.
   A. is waiting B. was waiting
   C. are waiting D. were waiting
【答案】B
【解析】句意：地震发生时，彼得和同学正在等公共汽车。选项A/C是现在进行时；选项B/D是过去进行时。根据when the earthquake happened. 地震发生时。彼得和同学正在等公共汽车。这一动作正在发生，因此句子Peter with his classmates ____ for the bus应该用过去进行时，排除A、C；又因为Peter with his classmates中的with表示伴随，因此本题的主语是Peter，为单数，所以be动词用was。故选B。