问题
选择题
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
答案
答案：C
题目分析：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。