I have a dilemma. I know how to use this, but I'm trying to explain it to someone and I can't find a logical explanation.

So here it is:

  1. Who called last night?
  2. Who did you call last night?

Why does the second sentence contain "did" when the first one doesn’t?

  • 2
    The second sentence is technically incorrect: it should be "Whom did you call last night?" However, many native English speakers confuse who and whom, and the intended meaning will be deduced from the word order rather than the case of the pronoun. – 200_success Nov 6 '14 at 11:22
  • Closely related: Do I have to use “do” in any “wh-” question? – apsillers Nov 6 '14 at 13:45
  • @200_ Well, and the form of the verb. – starsplusplus Nov 7 '14 at 0:01

Michael Swan explains this clearly in his Practical English Usage (2005.481).

When who, which, what or whose is the subject (or part of the subject), do is not normally used: Compare:

  • Who phoned? (Who is the subject.)
  • Who did you phone? (Who is the object.)

[...] But do can be used after a subject question word for emphasis, to insist on an answer:

  • Well, tell us - what did happen when your father found you?
  • This makes it pretty clear, but I have one more curiosity. What is the subject in your second example? Is it "you"? – Alex Nov 6 '14 at 11:48
  • @ Alex. Yes it is. – tunny Nov 6 '14 at 12:25

If the Wh- word represents the subject then we don't need to use do, and we don't need to change the subject and auxiliary verb.

However, It can be a bit difficult to understand if who/which is the subject. One way to find this information is to give a full answer to the question:

  • X called.
  • I called X.

If X is the subject of the answer, then it's usually the subject of the question, and we don't need do here. If it isn't the subject we need do:

  • Who called
  • Who did I call?

Hope this is helpful!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.