普通英文問題-upon

一般來說，On與upon都能通用，但upon往往較嚴，也多在以往的英文作品出現，至於on與upon的真正細微分別，英文學者古德明，在征服英語解答作者時，曾有以下分析

問: Upon通常可取代 on,但以下兩句可以改用 upon嗎?──( 1) The German soldiers were marching on Moscow(德軍正向莫斯科前進)。( 2) The summer holiday will soon be on us(暑假快來了)。

答: On和 upon作介系詞( preposition),一般可以通用,只是 upon語氣較為謹嚴。讀者示下的兩句, on都可以改為 upon,意思是「向着」或「逼近」,謹多舉兩個例子:( 1) He turned his back on/ upon me(他轉過身,背向着我,不瞅不睬)。( 2) The Japs were coming on/ upon us in force(日寇大舉來犯,逼近我們了)。

On和 upon兩字解作「在……之上」的時候,有一點值得注意: upon多指「由某處走到……之上」這動作, on則多指「已經在……之上」這狀態,例如: I was sitting on the sofa when the cat suddenly jumped upon my lap(我坐在沙發上,貓兒突然跳到我膝上)。留意 to jump upon my lap一般指「跳到我膝上」, to jump on my lap則既可以指「跳到我膝上」,也可以指「在我膝上跳」。

此外,說「很多」或「接連一個又一個」,通常會用 upon,較少用 on,例如:( 1) That is sophistication upon sophistication(那是詭辯連篇)。( 2) Row upon row of soldiers stood on the plain(平原上站着一排又一排士兵)。

又 once upon a time(從前)、 on page X(在第 X頁)這兩個說法, upon不可改為 on, on也不可改為 upon。

(古德明)

希望幫到你！

2012-07-27 11:25:16 補充：
Ling姐:

其實look down on是可以的
如
Cambridge Dictionary online就有以下一例：

She thinks they look down on her because she didn't go to university

upon普遍見到既意思= similar to on but not exactly the same so we cannot change upon to on as it may sound funny or strange in some cases

upon request = on request
upon receipt of something = on receipt of something
look down upon you = 看不起你 - cannot use on
Once upon a time = 從前 或 很久以前- cannot use on.

We will learn it naturally once you read more books or magazines