表示时间的区别：
at指时间表示：
1. 时间的一点，一时刻：
They come home at surprise (at noon, at midnight, at ten o’clock, at daybreak, at dawn).
他们出其不意地回家（中午、午夜、十点钟、黎明）。
2. 较短的一段时间。可指某个节日或认为一年中标志大事的日子。
His grandfather died at seventy-two.
他祖父七十二岁去世。
At the beginning (middle, end) of that month he was sick.
那个月初（中、末）他病了。
He went home at Christmas (at New Year, at the spring Festival, at night, at midsummer).
他在圣诞节回家（新年，春节，晚上，仲夏）。
in指时间表示：
1. 在某个较长的时间（如世纪，朝代，年，月，季节，及泛指的上午，下午和晚上等）内。
He died in the holidays.
他在假期去世了。
He was born in 1942.
他出生于1942年。
2. 在一段时间之后。
He will come round in a day or two.
他一两天后就会回来。
I will finish it in three hours.
我将在三小时内完成它。
on指时间表示：
1. 具体的时日和一个特定的时间，如某日，某节日，星期几等。
He will come to meet us on our arrival.
我们一到他就来接我们。
On May 4th (On Sunday, On New Year’s day, On Christmas Day), there will be a celebration.
5月4日（星期天，元旦，圣诞节），会有庆祝活动。
2. 在某个特定的早晨，下午或晚上。
He arrived at 10 o’clock on the night of the 5th.
他是5日晚上10点到的。
He died on the eve of victory.
他在胜利前夕去世了。
3. 准时，按时。
If the rain should be on time, I should reach home before dark.
如果下雨的话，我应该在天黑之前到家。
表示地点的区别
in 表示地点
1. in 表示比较大的地方
in Shanghai
in London
in Beijing
2. 虽然是很小的地方，如果说话人住在那里，也可用in，商店，机关，学校等，若看作一个地点（point)用at，若看作一个场所（place)用in。
I met him at the post-office.
我在邮局遇见他。
I’m now working in the post-office.
我现在在邮局工作。
On表示地点
一般指与面或线接触：
1. “在…上面”
He put the book on the table and sat on the chair.
他把书放在桌子上，坐在椅子上。
The picture was hanging on the wall.
那幅画挂在墙上。
2. “在…… 旁边”
NewYork is on the Hudson River.
纽约在哈德逊河畔。
Xiamen is on the river.
厦门在河边。
He lives in a house on the river.
他住在河边的一所房子里。
常用短语
在英语中介词的使用频率比较高，而介词in, on和at又是介词中使用频率比较高的词，收集了介词in, on 和at表示时间，地点和状态的常见的短语, 请注意一些短语用不同的介词，意义不同，有些区别不大。
表示时间:
in 表示时间
in 1999, in 20 century, in a flash(瞬时),
in a lucky hour(在幸运时刻), in a minute,
in a second, in a short time, in a while,
in a wink(一瞬间) in advance(预先),
in an emergency(在紧急地时候), in an evil hour(在不幸地时刻), in an instant, in ancient times, in broad day(在大白天),
in course of, (在…期间), in December,
in due course(及时地), in future, in good season(及时地),
in no time(马上), in one's childhood, in one's spare time,
in one's teens, in one's youth, in recent years,
in season(适时), in seconds(在很短的时间),
in some cases(有时候), in spring, in the afternoon,
in the beginning, in the daytime, in the end, in the evening,
in the future, in the long run(最后), in the meantime,
in the morning, in the nick of time(在紧急关头), in the night,
in the past, in the thick of (在最激烈的时刻),
in the thick of(在最激烈的时刻), in this period, in those days,
in time of war, in time
on 表示时间
on a certain day, on a sudden(突然), on a winter morning,
on Christmas Day, on night shift, on one's birthday,
on schedule(按时), on Sunday, on that date, on the eve of,
on the following day, on the instant(马上),
on the moment(立刻), on the Monday morning,
on the New Year's Eve, on the next morning,
on the point of(正在…时候), on the spur of the moment(立刻) on this day, on this occasion, on time
at 表示时间
at a time(在某时), at a wedding(婚礼), at all times(一直),
at any moment, at any time, at Christmas, at dark (天黑时),
at dawn(在黎明), at daybreak, at dinner-time, at dusk(在黄昏), at Easter, at first sight,(一见到), at first, at last, at midnight,
at night, at nightfall, at noon, at present, at six clock,
at sunrise, at sunset, at that moment, at that time,
at the age of, at the beginning of , at the correct time,
at the end of, at the last minute, at the moment,
at the present stage at the same time, at the stage(眼下)
at the start, at the time being, at the time of, at the very start, at this point(此时), at this season, at this time of day,
at times(有时）
表示地点
in 表示地点
in a car, in a queue, in advance of (在…前面),
in all the direction, in appearance, in corners(在角落里)
in doors, in front (of), in good light(在光线好的地方),
in heaven, in place(position)(在适当地位置), in places(处处),
in port(在港内), in public places, in shore(靠岸), in society,
in the air(在空中) in the bank, in the book(书的内容里),
in the centre(在中央), in the countryside,
in the distance(在远处那边), in the east of(在…东部)
in the east, in the fields, in the film, in the front rank(在前列),
in the front row, in the lab, in the letter(信的内容),
in the middle of, in the moonlight,
in the newspaper(报纸的内容里), in the open air(在户外),
in the open(在野外), in the picture, in the rain, in the room,
in the shade of, in the sky, in the suburbs of, in the sunshine, in the tree, in the universe, in the vicinity of(在附近),
in the warm(在暖和的地方) in the world, in(on) the bus,
in(on) the street
on 表示地点
on board (在船上) on camera(出现在电视上), on campus,
on deck(在甲板上), on earth, on 表示地点 on high(在高处),
on land, on the bank, on the beach, on the borders,
on the ceiling, on the coast, on the committee,
on the corner(在拐角处), on the east of(在…的东面)
on the farm, on the first floor, on the footba
