The film for half an hour.A. has begunB. has been onC. hasn’t begunD. began

问题补充：

The film for half an hour.

A. has begun

B. has been on

C. hasn’t begun

D. began

答案：

A. has begun

(答案→)B. has been on

C. hasn’t begun

D. began

解析：句意:电影已经开始半个小时了。根据句意可知，电影已经开始了，但是begin 是一个瞬间性动词，它不能和一段时间状语连用，而这句话中有for half an hour，所以可以排除A、C和D。故选B。