Yes/No Questions
Learn how a yes/no question is formed by moving an auxiliary verb before the subject, how do, does and did are added when needed, and how short answers work.
Asking for confirmation
A yes/no question can be answered with a single word.
A yes/no question asks for confirmation, and it can be answered with yes or no. It is formed by moving an auxiliary verb in front of the subject.
In the sentence Is she coming to the meeting?, the auxiliary verb is comes before the subject she, signalling that a question is being asked rather than a statement being made.
When a sentence has no auxiliary verb of its own, a form of do is added to carry out the same inversion.
Before you begin
Yes/no questions are one pattern of question formation.
This lesson focuses on yes/no questions specifically. Question formation as a whole includes three other patterns, each covered in its own lesson.
If you would like an overview of how questions are formed in general, begin with the Question Formation page.
The central idea
The subject and the auxiliary verb switch places.
Compare a statement with the same sentence turned into a yes/no question.
01
Statement
She is coming to the meeting.
02
Yes/No Question
Is she coming to the meeting?
The useful question is: which word is the auxiliary verb?
Once the auxiliary verb is identified, forming the question is a matter of moving that one word in front of the subject. The rest of the sentence stays in place.
When an auxiliary verb is already present
Move the existing auxiliary verb before the subject.
With be
Are they ready?
A form of be moves before the subject.
With have, used as an auxiliary
Have you finished?
A form of have used with a main verb moves before the subject.
With a modal verb
Can she swim?
Modal verbs such as can, will, should and must move before the subject in the same way.
When there is no auxiliary verb
Do, does or did is added to carry out the inversion.
Present simple: do or does
Does she work here?
Does is used with a singular subject; do is used with a plural subject or I and you.
Past simple: did
Did she work here?
Did is used regardless of the subject.
The main verb returns to its base form
She worked here. → Did she work here?
Once do, does or did carries the tense, the main verb no longer needs its own ending.
Negative yes/no questions
A negative form can express surprise, or expect a particular answer.
The contracted form
Isn’t she coming?
The contraction moves before the subject as a single unit.
The full form
Is she not coming?
Not stays after the subject when the full, uncontracted form is used.
Short answers
A yes/no question is usually answered with the same auxiliary verb.
Is she coming? → Yes, she is. / No, she isn’t.
Do they agree? → Yes, they do. / No, they don’t.
Did he call? → Yes, he did. / No, he didn’t.
The main verb is not repeated
A short answer repeats the auxiliary verb from the question, rather than repeating the entire sentence.
A useful decision guide
Ask whether an auxiliary verb is already there.
01
Does the statement already have an auxiliary verb?
Look for a form of be, have, or a modal verb.
02
If not, what tense is the main verb in?
Present simple takes do/does; past simple takes did.
03
Should the question be positive or negative?
A negative form can express surprise or expect a particular answer.
04
How should the answer be given?
A short answer reuses the same auxiliary verb from the question.
Common mistakes
A yes/no question needs exactly one auxiliary verb before the subject.
Do or does is not added when an auxiliary verb already exists.
Not: Does she can swim?
Correct: Can she swim?
The modal verb can already carries out the inversion; a second auxiliary is not needed.
The main verb keeps its base form after do support.
Not: Does she works here?
Correct: Does she work here?
Does already shows the present tense, so the main verb does not take its own -s ending.
The subject and auxiliary verb must actually switch places.
Not: She is coming?
Correct: Is she coming?
A question mark alone does not form a yes/no question; the auxiliary verb needs to move before the subject.
Check your understanding
Which auxiliary verb completes each question?
Choose the correct answer for each sentence.
__________ he live near the station?
✅ Exactly! He is a singular subject, so does is needed.
❎ Not quite. Check whether the subject is singular or plural.
Is the subject one person, or more than one?
__________ you seen this film before?
✅ Exactly! Seen is a past participle, so have is the auxiliary verb needed.
❎ Not quite. Look at the form of the main verb, seen.
Which auxiliary verb pairs with a past participle?
__________ they arrive on time yesterday?
✅ Exactly! Yesterday signals the past simple, so did is needed.
❎ Not quite. Look for a word in the sentence that signals when the action happened.
What tense does yesterday point to?
Choose the best explanation
Select the sentence that explains the question correctly.
Why is “Does she can swim?” not correctly formed?
✅ Exactly! A sentence needs only one auxiliary verb moved before the subject.
❎ Not quite. Look at how many auxiliary verbs appear before the subject.
Why does “Does she works here?” need to be corrected?
✅ Exactly! Does already carries the present tense, so works should return to work.
❎ Not quite. Look closely at the ending of the main verb.
Try it another way
Complete each short answer.
Type the missing word.
✅ Exactly! The short answer reuses the same auxiliary verb from the question.
❎ Not quite. Reuse the auxiliary verb from the question itself.
✅ Exactly! Didn’t matches the auxiliary verb did used in the question.
❎ Not quite. Use the negative form of the auxiliary verb from the question.
Quick review
A yes/no question moves an auxiliary verb before the subject.
A yes/no question requests confirmation and can be answered with yes or no.
If the statement already has an auxiliary verb, such as be, have, or a modal verb, that verb moves before the subject.
If there is no other auxiliary verb, do, does or did is added, and the main verb returns to its base form.
A negative yes/no question, such as isn’t she coming?, can express surprise or expect a particular answer.
Short answers reuse the same auxiliary verb from the question, rather than repeating the whole sentence.
Remember
Find the auxiliary verb first, then move it before the subject.
If a statement already has an auxiliary verb, move it. If it does not, add do, does or did, and let the main verb return to its base form.