Since I still get the question, I should cover the rule that many experts have already answered: Can you use a preposition to end a sentence with? (I suppose I could have written, "Can you end a sentence with a preposition?" but I couldn't resist.) Here's the short answer: Yes.
And now for the longer answer: Only a grammar snob or an inexperienced writer would hold fast to such an arbitrary rule. Even the Oxford Dictionary Online sees no point in this rule. True, we would do well to make our sentences more concise, as in these sentences:
Wordy, Awkward: What should I do this for?
Concise, Fluent: Why should I do this?
Wordy, Awkward: Where does this go to?
Concise, Fluent: Where does this go?
But in the sentences below, the sentence ending with the preposition is better than the alternative:
Awkward: To whom should I give this?
Fluent: Whom should I give this to?
Awkward: At what are you looking?
Fluent: What are you looking at?
Books by Philip Vassallo