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 ,
