Anyone seeing any problem with:

Who did open the door?


Who opened the door?

Do both convey same message?


3 Answers 3


Answer to the question in a context.

Paul: Who opened the door?

John: Peter opened the door.

Paul: No, he didn't open the door. I was here all afternoon and did not see him do it.

John: Well, then who did open the door?

The did is used with who + did [auxilliary]+ main verb to emphasize the question when the question is reposed, for example, after the answer by one person is questioned by another or in response to a negative statement by a person.

Paul: If he didn't do it, who did [do it:implied]?


Using the auxiliary verb (did open) provides a mechanism for emphasis (as in If it wasn't you, then who did open it?). Note that if there's no "helper verb" such as did here, you'll often find that emphasising the "primary" verb carries a different emphasis (I closed the door, but I don't know who opened it). If you don't want to be able to emphasise in this way, don't use did (non-emphatic use of this construction is usually archaic).

[transcribed from comment]


Who opened the door?

Is a subject question, meaning it is searching for the subject of the action of the verb. We do not typically use auxiliary verbs in subject questions. We use them in other types of questions. For instance:

  • "Where did you go?"
  • "What do you eat for lunch every day?"
  • "Where did you meet him?"


  • "Who broke the vase?"
  • "Who washes the dishes in you house?"

Related web page at Learning English British Council

  • 2
    We don't have to use the auxiliary in a subject question, but we may do so (as FumbleFingers says in a comment) for emphasis, or more particularly for contrast. "Who did open the door?" is common as a response to "I/he/Jane didn't open the door".
    – Colin Fine
    Oct 28, 2018 at 17:33
  • I have to disagree with you Colin Fine. "Who did open the door?", is not at all natural. learnenglish.britishcouncil.org/en/beginner-grammar/…
    – Terry
    Oct 28, 2018 at 17:40
  • 1
    And I have to disagree with you, @Terry. The fact that a particular page of an elementary grammar does not mention a construction is hardly evidence that the construction is unnatural. The "advanced level" section of this has examples of do for emphasis in statements, though not in questions. I admit I'm surprised at how few instances of "Who did [verb]" I can find in the online corpora; but a couple of examples from there are "Who did invent radio?" and "Who did write the bible?". They seem quite natural to me.
    – Colin Fine
    Oct 28, 2018 at 18:22
  • Thank you Colin Fine. Yes, emphasis in questions is not that common online as you pointed out. @Lambie's answer put things in the right perspective for me. Thank you everyone.
    – Terry
    Oct 28, 2018 at 18:38
  • @Terry - Absent any additional context, though, I'd agree with the main thrust of this answer. If you changed the rigid, "We do not use auxiliary verbs in subject questions," to a more flexible, "We do not typically use auxiliary verbs in subject questions," then I might be inclined to upvote the answer.
    – J.R.
    Oct 29, 2018 at 0:09

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