The boy was observed basketball at eight o’clock yesterday. A. playingB. playC. to playD.

问题补充：

The boy was observed basketball at eight o’clock yesterday.

A. playing

B. play

C. to play

D. having played

答案：

(答案→)A. playing

B. play

C. to play

D. having played

解析：可联系答.案.网客服索取。