My sister met him at Ningbo Grand Theatre yesterday afternoon, so he your lecture.
A. couldn’t attend
B. mustn’t have attended
C. shouldn’t attend
D. couldn’t have attended
网友回答
A. couldn’t attend
B. mustn’t have attended
C. shouldn’t attend
(答案→)D. couldn’t have attended
解析： 从上文可知，句子叙述的是已经发生过的事情，故用完成时态，mustn’t have done表示禁止的意思，故选D，以此他不可能参加过你的演讲。