Which is/are the correct usage(s):

  1. "What is that key for?"
  2. "What for is that key?"
  3. "For what is that key?"

First one looks correct. But what about others? Also, it would be better if you can explain.

  • 2
    You can pied-pipe a preposition with a Wh-word as in (3), but it's awkward and more complex than (1), so it would be avoided. (2) is right out, because what for?, by itself, is a synonym for why?, and you can't say *Why is that key? Jul 12, 2017 at 19:54
  • 1
    The root question is "That key is for what?" (1) fronts the query pronoun (and an auxiliary verb), which is normal. (3) fronts the pronoun along with its preposition, which is clumsy. (2) fronts the pronoun twice {first like (3), then like (1)} which is not allowed {the meaning is not what was intended}.
    – amI
    Jul 12, 2017 at 20:44
  • 1
    I don't think 2 is okay, 3 is archaic. Jul 12, 2017 at 22:03
  • 3
    @marcellothearcane Totally agree. Do not make the mistake of not ending with a preposition simply because of some (also) archaic rule that prepositions cannot be at the end of sentences. If it helps the meaning then you absolutely can use one. #1 is correct.
    – Kace36
    Jul 12, 2017 at 22:23
  • 2
    Regarding Winston Churchill and a famous quote: After an overzealous editor attempted to rearrange one of Winston Churchill's sentences to avoid ending it in a preposition, the Prime Minister scribbled a single sentence in reply: "This is the sort of bloody nonsense up with which I will not put.". It was done and said to show how ridiculous it is try to avoid a preposition at the end of the sentence. See how bad the meaning becomes and loses its context completely? He wants to say instead: "....sort of bloody nonsense which I will not put up with".
    – Kace36
    Jul 12, 2017 at 22:28

2 Answers 2


What is that key for? is correct. It's what people say and write. The other two examples are not constructed as English speakers would say them. In fact, the second one is quite wrong. The third one might once have been considered correct as there is a misguided perception that sentences should not end with a preposition. From The Chicago Manual of Style Online 5.180:

The traditional caveat of yesteryear against ending sentences or clauses with prepositions is an unnecessary and pedantic restriction. And it is wrong. As Winston Churchill is said to have put it sarcastically, “That is the type of arrant pedantry up with which I shall not put.” A sentence that ends in a preposition may sound more natural than a sentence carefully constructed to avoid a final preposition. Compare, for example, This is the case I told you about with This is the case about which I told you. The “rule” prohibiting terminal prepositions was an ill-founded superstition based on a false analogy to Latin grammar. Today many grammarians use the dismissive term "pied-piping" for this phenomenon.

I have not included a link, as CMOS is behind a paywall.

  • 1st sentence is correct, common and widely used.
  • 2nd sentence is incorrect, period.
  • 3rd sentence is obsolete and uncommon but correct.

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