有日用on,无日用in,具体时间用at
on Sunday ,on Sunday morning ,on a sunny morning,on Jan.1st
in the morning,in a year,in a month ,
at ten o'clock ,at the moment,at noon,at night
地点
on the desk ,on the river ,on the wall
in the street ,in the river ,in the room,in Beijing
at the table ,at the bus stop ,