Question

The boys           when the teacher came in. So she was very angry．

A．were doing homework

B．were cleaning the classroom

C．were fighting

D．were learning English

Answer 1

C

试题分析：句意：当老师进来时那个男孩正在打架，所以老师非常生气。when 引导的从句表示一个时间点，强调在这个时间点上另一个动作正在发生，故用过去进行时。根据句意，故选C。