You are too late. The film since half an hour ago. A. has begun B. has been onC. beganD.

问题补充：

You are too late. The film since half an hour ago.

A. has begun

B. has been on

C. began

D. begins

答案：

A. has begun

(答案→)B. has been on

C. began

D. begins

解析：考查时态。句意“你太晚了。电影已经开始半小时了。”since从句表示一段时间，前面用现在完成时，begin是短暂性动词，不能与一段时间连用，需要转换为be on。故选B。