好難分呀...........

preposition總共有42個
A: about, above across, after, against,along, alongside, amidst, among(st) , around, at

B: before, behind,below, beneath, beside, besides,between, betwixt, beyond, but, by

OTHER : down, for, from, in, into, of, off,on, out of, over, through, throughout, to, toward(s), under,underneath, up, with, within, without

Prepositions may belong to one of these types:
1) Place / Position
Eg: They are "at" the grocery shop

2) Direction/ Movement
Eg: She drove "around" the town

3) Time
Eg: She war born " in" 1960

4) Means/Manner
Eg: Some shops were destroyed "by" fire

5) Reason/ Purpose
Eg: She lost her purse "through" neligence.

自先你看一看以下一段的解釋：
Prepositions of Time: at, on, and in
We use at to designate specific times.（我們會用at在指定的時間）

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
The train is due at 12:15 p.m.
We use on to designate days and dates.（我們會用on在指定的日子／或星期幾）

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
My brother is coming on Monday.

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
We're having a party on the Fourth of July.
We use in for nonspecific times during a day, a month, a season, or a year.（我們會用在一日，一月，一季，或一年並未指定的特定的時間）

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
She likes to jog in the morning.

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
It's too cold in winter to run outside.

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
He started the job in 1971.

圖片參考：http://grammar.ccc.commnet.edu/grammar/gif/cleardot.gif
He's going to quit in August.
這樣的解釋，我相信你已經明，但要記得night, noon是非常特別，都要用at night和at noon.而不像morning或afternoon是用in，如in the morning, in the afternoon
另外，eve 前面是必須用on，如:on christmas eve； 而節日多數用at,如at new year, at christmas, at dragon boat festival等等
現在大約幫你分：
at 12:30 p.m.; at 3 o'clock, at night, at noon, at chrstmas
in 1990, in summer, in the morning, in September
on Friday, on the Fourth of July, on New year's eve

Year -- "in” e.g. in 2007
Month -- "in” e.g. in January
Day -- "on” e.g. on 1st of July 1997, on Tuesday, on 23.4.2007
Time -- "at” e.g. at eight o'clock, at half-past one, at 7:45am
"in” the morning
"in” the afternoon
"at” night

但是，有時要視乎你想表達甚麼
e.g., yesterday morning, last night, tomorrow night, next Friday, one day, one morning, one night, 等是不需要preposition的

又例如 "in the night of 10.4.2007", night 之前要用 "in the", 唔用"at” 或"on”