The TV program has begun since half an hour ago(同义句)

问题描述:

The TV program has begun since half an hour ago(同义句)
The TV program_____ _____ _____ _____half an hour
最后一个空是for吧?那前三个是什么?这是我们学校发的预习题,所以麻烦讲解清楚一点~

has been on forbe on 不是上映么?是的,但是这里用的是现在完成时态