英文困擾?????

樓主的困擾十分典型。事實上，這些前置詞(prepositions)的用法沒有金科玉律可供記誦，它們的用法大多為約定俗成，不過仍有一些大致的規則可以作為原則。
"at"約等如中文的“在......一個地方或一件物件的意思”，例如"She looks at me".
"in"約等如中文“在......之內的意思”，例如"I lost my wallet in school".
"for"約等如中文“為了一個人或一件物件而做”，例如"I do it for you", "This cake is specially for you".
"about"約等如中文“關於一個人或一件事”，例如"I tell you somethin about Mary", "This story is talking about a little boy how to overcome his learning difficulties."
"on"約等如中文“在......之上的意思”，例如"This book is left on the table", "Peter stands on the stage and sings a great song".
當然，這些前置詞的特定用法多不勝數，有些情況也很難分類或只能靠死記，但大致上它們的用法都如上所說。最重要的還是要多讀多記多思考，才可用好它們。

at, on, to, for 都係preposition. 我亦都唔多講解咩野係preposition啦~ 直接解釋一下 on, at, to, for.

與時間有關的preposition (Prepositions of Time)
"AT" is used to show an exact time
at 用來表示正確時間
e.g. at one o'clock (在一時), at this moment (現在), at noon (在正午), at the same time(同時)

"ON" is used to show a more general point of time
on 用作表示特殊時間
e.g. on Friday night(在星期五晚), on Wednesday(在星期三), on his birthday(在他的生日)

"FOR" is used to show how long an action lasts.
for 用作表示動作能維持的時間
e.g. for three months (<用>三個月), for ten years (<用>十年), for five minutes (<用>五分鐘), for four weeks(<用>四星期)

與地點有關的Prepositions (Prepositions of Place)
"AT" is used to show the exact place
e.g. at home(在家), at the table(在桌上), at school(在學校)

"IN" is used for a larger area
in 用作表示範圍大的地方
e.g. in the room, in Hong Kong, in the kitchen

"ON" is used to express one thing resting on another
on 用作表示物件在另一東西之上
e.g. on the table, on the floor, on the road

"TO" 多數指地方, 而to 通常都放左名詞(地方or人名)的前面
e.g. to you, to Hong Kong, to me, to Japan

當然prepositions的用法還有很多,不過e家學好基本再學難d唔洗咁辛苦

example:
at
At six o’clock, at closing time.

on
Born on the 4th of July.

to
I want to leave.

for
The astronauts headed for the moon.