at college与in a college的疑问

许国璋英语第一册269页：

1.He studies in a college in Peing.

2.How is his life at college ?

同是在college一词前面，为何一会儿用in,一会儿用at，根据是什么？

English___in a new way at my college in the past few years. 请问“I am in my first year at college."..... in a 和at a 的区别 英语中at 与in once in a while 与occasional, at times, sometimes的区别 请问:in the shop与at a shop有什么区别?? she have been going to college, a few courses at a time, for 27years. marrige in college 64. To tell you the truth, i became a college student at 15. If you had studied hard at school, you would be a college student now.