1、in, on, at表时间

　　in "在某月(季节、年)等" eg:in 1996, in January, in summer

　　固定词组：in the morning,       in a week,in a minute,in time, in the end

　　on "用于指具体的某一天或专指某一天上午、下午或晚上等"

　　eg:on Christmas Day, on the night of February 16

　　at "用于具体时刻前和某些固定词组中"

　　固定词组：  at seven, at the moment, at night, at last, at first, at noon,

　　at times, at once,  at this time of the year,\at the beginning of,

　　at the end of this month,

　　at the same time

　　注意：the day before yesterday和the day after tomorrow 前不用介词

　　通过媒介 on /over the telephone,  on /over the radio,  on TV