at college与in a college的疑问

at college与in a college的疑问 at college /in college 的区别 in college 和 at college in college与in the college的区别 go to college 的延续性 是be at college 还是 be in college at college in school/ at college/ in university/ on a gap year 的区别 David___ (study) at a college in China now . at a college和at college有什么区别吗还有in a university和in university 上大学是说成是be in college 还是be at college 是be in college 还是be at college This was at a college-level with hungry college student.