What do you often do Sunday morning?A. atB. onC. inD. /

问题补充：

What do you often do Sunday morning?

A. at

B. on

C. in

D. /

答案：

A. at

(答案→)B. on

C. in

D. /

解析：句意：你经常在周日上午做什么?,在周几，或周几的上下午，用on.故选B