介词 on at in 表时间 at 时间最短，一般表示点时间，具体的某个时刻1.at six o’clock2.at 8:30习惯用语： at night at noon at this time of year On ‘ 在具体某一天’ 及 ‘具体某一天的上午 下午 和晚上’1.On mother’s Day ,we should send flowers to our mother.2.On Monday/Friday/Saturday……3.On Tuesday afternoon On Sunday morning (evening)4.On July 1,1999 On March 7<1>On + 星期 (1----7)<2>On + 年，月，日 / 年，日 / 月，日 In 时间范围大（一天以上）1.in spring/ summer/ autumn/ winter2.in 1999/ 2012 in May ,20123.in the morning /afternoon/ evening 4.in September/ May/ June/ July5.in a year in a week1 > in + 四季2 > in + 月份3 in + 年 / 年，月 / 月 At <1 天 In >1 天 On=1 天 介词 on at in 表方位 at 把地点，地方，位置当做一个‘点’1.He is at home.2.He is waiting for you at the bus stop.3.Who’s standing there at the door.4.I’m in France,at paris. On 把地点，地方，位置当作一个平面1 There was a ‘No Smoking’ sign on the wall.2I live on the 7th floor at 21 Oxford street in London.3You are standing on my foot.4 There are no prices on this menu. in 把地点，地方，位置当作一个范围或一个封闭的空间1.I live in London2.I live in England, at London. < 大城市用 in ，小城市用 at>3.I live in a big city,my sister lives at a small town.
