What is this? What is that? Do you know? Have you found out yet?
The formation of questions in English is a source of much confusion for many learners. Why do we sometimes use do and sometimes not? We're going to break down how we form questions and fix some common mistakes that seem to plague so many of our sentences.
1 Questions using be, have, auxiliary verbs, and modal verbs.
Questions whose main verb is be do not use do, but do require inversion. What is inversion? Inversion is when you swap the order of words.
Ex. You are a doctor. (statement) Are you a doctor? (question)
The same thing goes for have ONLY when have is an auxiliary verb.
Ex. You have finished your chores. (statement) Have you finished your chores? (question)
Inversion also happens with modal verbs
Ex. He could run for office. (statement) Could he run for office?
*Sentences which use have as a main verb or any other main verb need do which brings us to our next rule.
2 Questions using main verbs
For questions using main verbs we have to insert do.
Do you know how to get to the station?
*Don't forget we ONLY conjugate the auxiliary verb
Does he come here often?
3 Subject/Object questions
When we have a question word that asks about the subject of the answer we do not usually use do.
Ex. Who runs this place? Who and he are the same person (Subject question—Do not use do)
-He runs this place.
Where do you live? Where and I are not the same (Object question—use do)
I live in Edinburgh.
4 Do for emphasis
Sometimes we can insert do into subject questions when we want to emphasize or are clarifying a piece of information
Ex. If I didn't leave the light on, and you didn't leave the light on, then who did leave the light on?
I do love this town (emphasized)