Do you know about Quora? It’s one of the best social networks in terms of questions and answers. Needless to say, there are numerous questions and answers about the English language. This is a particularly good example:

QUESTION

Is it true that you can’t end a sentence with a preposition?

ANSWER

Classic Ivy League joke:
Visitor in Harvard Square: “Excuse me, where’s the library at?”
Harvard student:  “Sir, this is Harvard. We don’t end our sentences with prepositions.”
Visitor: “Oh, I’m sorry. I meant to ask, where’s the library at, idiot?”