upon

1、upon 就是 up + on 合成，意思基本等于 on，只是更书面、更正式，日常能换 on 的地方多半换。
2、固定说法最值钱：Once upon a time（从前，童话开头）；look upon A as B（把 A 看作 B）；the pressures of modern life upon us（现代生活压在身上）。
3、后面接动作时用 upon doing：Upon arrival, he...（一到就……），这种句子在考试阅读里常见。

upon 在上面

来自短语up on.

upon (prep.)

early 12c., from Old English uppan (prep.) "on, upon, up to, against," from up (adv.) + on (prep.); probably influenced by Scandinavian sources such as Old Norse upp a.

upon (adv.)

Old English upon; see up (adv.) + on (prep.).

1. Remember, happiness doesn't depend upon who you are or what you have; it depends solely upon what you think.--Dale Carnegie

请记住，幸福不在于你是谁或者你拥有什么，而仅仅取决于你的心态！

2. He was holding a cloth that dripped pink drops upon the floor.

他正拿着一块布，布上粉红色的水滴落在地板上。

3. I imagined the eyes of the others in the room upon me.

我觉得屋里其他人似乎都在盯着我。

4. Do you think she could be prevailed upon to do those things?

你觉得有可能说服她去做那些事情吗？

5. The city was walled and built upon a rock.

这座城市建在岩石上，四周筑有城墙。