Don't end a sentence with a preposition!

剛剛在書上看到一個挺有趣的笑話：

A: Where's the theatre at? 

B: My good man, don't you know that one doesn't end a sentence with a preposition? 

A: Well, where's the theatre at, jackass? 

[Note: a jackass = a stupid person]

的確，在 formal English 裡，我們不要把 preposition 放在句尾，除非那 preposition 屬於 phrasal verb 的一部分，例如 take off (起飛), carry on (繼續) 和 win over (說服)。

譬如說： 

The plane has taken off. 

這句話沒問題，因為 preposition "off" 屬於 phrasal verb "take off" 的一部份。

如果是： 

Peter is the person I played with.    

在 formal English 裡，我們應該把它寫成： 

Peter is the person with whom I played.    

當然，如果是會話式英文，Peter is the person I played with 這句話就沒有問題了。