从句中,如何判断用过去完成时还是现在完成时?看这一题：The film __________ for ten minutes when I reached the hall.是用has been on 还是用 had been on 如果是He said that the film ________ for ten minutes when he reached the hall.应该选什么?应不应该改成：when he had reached the hall.练习册上答案是had been on.能不能举一个用 has been on 的例子呢？

从句中,如何判断用过去完成时还是现在完成时?
看这一题：
The film __________ for ten minutes when I reached the hall.
是用has been on 还是用 had been on
如果是
He said that the film ________ for ten minutes when he reached the hall.
应该选什么?
应不应该改成：when he had reached the hall.
练习册上答案是had been on.
能不能举一个用 has been on 的例子呢？