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When do I use is or does when I ask a question? For example,

  • Is your item still for sale?
  • Does your item still for sale?

I am not sure which one to use.

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  • 14
    Turn your question back into a statement and see which one fits. The item is for sale OR The item does for sale. Since it is The item is for sale then the question is: Is the item for sale?
    – Jim
    Oct 1, 2013 at 4:26

2 Answers 2

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When the verb in a statement is neither a primary auxiliary verb (be, have, do) nor a modal auxiliary verb (will, would, can, could, may, might, shall, should, must, ought to, used to), do is used to form a question from it. Thus, ‘You know where my house is’ becomes ‘Do you know where my house is?’

Meanwhile, when the verb in a statement is a primary auxiliary verb or a modal auxiliary verb, then a question is formed from it by placing the verb before the subject. That means that ‘Your item is still for sale’ becomes ‘Is your item still for sale?’

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  • *Used you to go? Oct 1, 2013 at 7:32
  • I normally insert normally somewhere, and should have done so here. As it is, the BNC has no records for used you to? used in this way. I don’t say no one ever says it, but my intuition is that did you use to? is what most people would say. Oct 1, 2013 at 7:53
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Barrie Englands answer is great. However, I have a feeling those seeking an answer will be at a level where they will also confused by the neither/nor structure.

For Primary auxiliaries (be/have/do), and Modal auxiliaries (will, would, can, could, may, might, shall, should, must, ought to, used to):
Simply reverse the statement to form the question.

For all others use ‘do’ to form questions:
Place the verb before the subject.

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  • Hello Bob & welcome to the site! I have made some minor changes to your post, mainly, because referring to "the other answer" might become misleading once more answers are given. Unlikely in this case, but not impossible...
    – Stephie
    Jan 8, 2015 at 7:56
  • @Bob, «For be/have/do — simply reverse the statement to form the question», it sounds like «You have a book → Have you a book?», but in fact it should be «Do you have a book?».
    – Mike
    Oct 23, 2019 at 18:23

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