Why ________ you always interrupt me when I am talking with my classmate? It is quite annoying．

Why ________ you always interrupt me when I am talking with my classmate? It is quite annoying．

A.must

B.shan’t

C.can’t

D.needn’t

答案及解析： A

解析：

本句的意思是：“我在和同学谈话时，你为什么非打断不可呢？”，只有must表示“一定、非……不可”这一含义，故选A项。