Everyone is busy _____ the examination in the classroom.

Everyone is busy _____ the examination in the classroom.
A、with
B、for
C、on
D、under
【正确答案】：A
【题目解析】：注意几个固定搭配： be busy (in) doing sth 忙于做…； be busy with sth 忙于…； busy oneself (in) doing sth 忙于做……； busy oneself with sth 忙于……。