我搜索了下，用 at 和用 in 的都有，有何区别呢？用 in 的比用 at 的大？又或者 at 表示在学校学习？in 仅仅表示地点？

1. Trouble is boiling up in the university. 这所大学正在酝酿着动乱。《21世纪大英汉词典》

2. He was appointed professor in the university for life. 他被任为那所大学的终身教授。《新英汉大辞典》

3. He has made considerable progress in his studies at the university. 他在大学的学业上有了长足的进展。《新英汉大辞典》

4. I really cannot imagine what my semester at the University of Oklahoma would have been like without him. 我简直无法想象，要是我在俄克拉何马大学的那个学期没有他会是什么样。