請問in,on,at三個介係詞的區別在哪?

in prep.:-
(in place);in the distance, in class, in the day time.in May 4,'44; in part of day, in period, in season.

on prep:-
on date;on Sunday (on date), on the morning of, on May 4th, on the instant.on month--day.

at prep:-
be present at the meeting, (at time), at noon, at five o'clock, at dinner, at work, quick at learning, at will.

in = 表達在東西"裏面"，當然這"裏面"除了物質東西外，也可以是"理念性"的裏面。
例如：In a month (In January)表達在一月"時空裏"，I ate in a very good restaurant (in a place)表達在餐廳"在某地點/地區裏"，I am in good shape (in a condition/situation)表達我很強健"在某狀態/戕況裏"。另外有些特別的意思：In time = 及時。

on = 表達在東西"上/上面"，當然這"上面"除了物質東西外，也可以是"理念性"的上面。
例如：On a mountain (on a place/location)表達在地點(質感或理念)高位置"上"，On Tuesday (on date)表達在某日"上"，On paper表達在紙"上"寫下來的 - 另一同義講法是in writing便用in表達是用字寫出來構成的"內"容。另外有些特別的意思：On time = 準時。

at = 表達在可以確定位置(指定)，當然這"指定"除了物質東西外，也可以是"理念性"的肯定。
例如：Stay at work at night (at a place/location, at a time)表達在地點(質感或理念)和時空(實際時間點或時段)"位置"，At 12 O'clock/At noon (at a time)表達在某時間，At home表達在家"裏" - 類同的通用地方是用at office, at school, at a shopping mall. at 跟 in 一個地方的分別是表達那地方的整體還是表達事件中的特性，例如：I ate in that restaurant.表達我食飯的位置是在那餐廳裏面 / I join my friends at that restaurant.表達我去跟朋友會合的地點(可能亦是食飯的地方)是那餐廳地點位置。 另外有些特別的意思：At times = 有時，時不時, 某時 (留意times是眾數表示遇然重複出現的時間)。