Which one of the following is correct use? If both are correct, what difference does this change make in a conversation?

  1. Do you know when is this being used?
  2. Do you know when this is being used?
  • 1
    Personally, I would never say is before this. Replacing "this" with a noun makes your 1 example sound wrong with every word I can think of off the top of my head.
    – Josh Lowe
    Commented Oct 3, 2016 at 19:18

1 Answer 1


In my opinion, the sentence is already in a question for "Did you...?" so the clause "when this is..." does not need to be in question form as well; it is just awkwardly worded. The word "when" is a conjunction and forms - along with the rest of the sentence - a dependent clause. If used separately, "When is this...?" would be correct. Hope this is helpful!

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