had been to 是什么时态

　　Oh, I had been to the airport that time.

　　哦，那时我已经去机场了。

　　My friend learned that the police had been to the flats.

　　我的朋友得知警察来过大楼。

　　I had been to Penn only one day, in October of my senior year.

　　我只在宾夕法尼亚州立大学呆过一天，那是在我毕业那年的十月份。