The film had been on for ten minutes when i got to the cinema

问题描述:

The film had been on for ten minutes when i got to the cinema
这里为什么用HAD BEEN 而不用HAS BEEN 呢

过去完成时 当我到电影院的时候 电影已经开始十分钟了 到电影院时就是过去时了 电影开演在那之前 是过去的过去 典型的过去完成时 构成是 had +过去分词