You are too late. The film since half an hour ago. A. has begun B. has been on C. began

问题补充：

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

A. has begun B. has been on C. began

答案：

解析：根据时间状语从半小时前，可知本句为完成时态。begin可以用于完成时，但是它是一个短暂性动词，后面不能跟一段时间。所以选B。