What do you call this elevated road structure?

I thought that a "Do" word was used whenever an action takes place.

I didn't see any action performed in any form, he is just asking a question.

  • Do functions as an operator the perfom a subject-auxiliary inversion. 'Do' has no meaning here; it's just a dummy (meaningless) function word. Commented Aug 15, 2017 at 8:00
  • do is a helping verb in the interogative sentence. Commented Aug 15, 2017 at 8:07

1 Answer 1


Do is not only used as an action verb, but also as an auxiliary verb. Which means, used together with other verbs as know, like, think etc. For example:

I don't know the answer.

I don't like pizza.

I used don't in the examples because in a positive statement, do is usually omitted:

I know the answer.

I like pizza.

Do is only used in these statements, when you want to emphasize the fact. I do like pizza, actually.

Do is also used in asking questions:

Do you like pizza?

Do you know which was Shakespeare's first play?

So using do in questions is perfectly fine.

In the question you cited, the only difference is that the asker didn't know the name of the road structure, so couldn't ask "Do you call this elevated road structure an overpass?" Instead, they asked "What do you call...".

  • 1
    Correct +1. But it's worth pointing out that we use 'do' because there's no auxiliary to perform the subject-auxiliary inversion. Commented Aug 15, 2017 at 8:21
  • What user178049 means is when you ask questions, you change word order. Like "You have visited England before" becomes "Have you visited England before?" But in sentences like "You know the answer" there is no auxiliary verb like "have" in the previous one, so we use "do" in place: "Do you know the answer?"
    – GregT
    Commented Aug 15, 2017 at 8:41

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