Why you keep on troubling me with such questions while Im busy ? A. could B. can C. mus

问题补充：

Why you keep on troubling me with such questions while I\m busy ?

A. could

B. can

C. must

D. will

答案：

A. could

B. can

(答案→)C. must

D. will

解析：must 在本句中表示“偏偏”，常用于以 you 作主语的疑问句中。