You should move back and forth while basketball.A. to playB. playingC. are playingD. play

问题补充：

You should move back and forth while basketball.

A. to play

B. playing

C. are playing

D. plays

答案：

A. to play

(答案→)B. playing

C. are playing

D. plays

解析：while 引导的是时间状语，当主句与从句的主语一致，故选答案为B