Auxiliary verbs (also called helping verbs) are essential in English grammar. They don’t show meaning by themselves but support main verbs to form verb tenses, questions, negatives, and the passive voice. Common auxiliary verbs include be, do, and have, as well as modal verbs like can, will, and must.
Understanding how to use auxiliary verbs correctly helps you speak and write more fluently in English. Whether you’re forming questions (Do you like pizza?), talking about time (She has finished), or adding emphasis (I do agree), auxiliary verbs appear in nearly every sentence. In this complete guide, you’ll learn what auxiliary verbs are, the different types, rules, and examples, and how they work in real English sentences.
What Is an Auxiliary Verb?
An auxiliary verb is a verb that supports the main verb in a sentence to express tense, aspect, voice, mood, or to form questions and negatives. Unlike main verbs, auxiliary verbs do not express a complete action or meaning by themselves—they function grammatically to help the main verb work properly.
Examples:
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She is working. → “is” is an auxiliary verb helping form the present continuous tense.
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We have finished our homework. → “have” helps create the present perfect tense.
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Do you like pizza? → “do” is used to form a question.
Auxiliary verbs are essential in English grammar and cannot be avoided if you want to speak or write fluently.
Types of Auxiliary Verbs
There are two main types of auxiliary verbs in English:
1. Primary Auxiliary Verbs
These include: be, have, and do. They help form different grammatical structures such as questions, negatives, and tenses.
a. Be – used to form continuous tenses and passive voice.
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She is studying. (Present Continuous)
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The letter was written by him. (Passive Voice)
Forms: am, is, are, was, were, be, being, been
b. Have – used to form perfect tenses.
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I have eaten lunch. (Present Perfect)
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They had left before we arrived. (Past Perfect)
Forms: have, has, had
c. Do – used in questions, negatives, and emphatic expressions.
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Do you like coffee? (Question)
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He doesn’t understand. (Negative)
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I do want to go! (Emphasis)
Forms: do, does, did
2. Modal Auxiliary Verbs
Modal verbs express meanings such as ability, possibility, permission, necessity, or advice. They are always followed by the base form of the main verb.
Common Modal Verbs:
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can, could – ability, permission
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may, might – possibility, permission
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will, would – future, polite requests
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shall, should – suggestions, advice, obligation
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must – strong obligation, necessity
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ought to, need to, used to – semi-modal auxiliaries
Examples:
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She can swim very well.
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You must finish your work.
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He might be late.
Important: Modal verbs do not change form (no -s, -ed, or -ing) and are not followed by “to” (except ought to, used to, have to).
How Auxiliary Verbs Function in English Grammar
1. Forming Verb Tenses
Auxiliary verbs help form all continuous and perfect tenses.
Examples:
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She is working late today. (Present Continuous)
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They have gone to the store. (Present Perfect)
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He was reading when I called. (Past Continuous)
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I had finished my homework before dinner. (Past Perfect)
2. Forming the Passive Voice
Auxiliary verbs—mostly forms of be—are essential for forming passive constructions.
Examples:
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The report is written by Sarah.
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Dinner was served at 8 p.m.
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These books have been read by many students.
3. Forming Questions
In questions, the auxiliary verb comes before the subject.
Examples:
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Do you like coffee?
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Is she coming to the party?
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Have they arrived yet?
Note: Modal verbs also help form questions:
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Can I ask you something?
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Should we leave now?
4. Forming Negatives
Auxiliary verbs are used with “not” to form negative sentences.
Examples:
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I don’t like spicy food.
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She hasn’t finished her work.
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We aren’t ready yet.
Tip: In spoken English, contractions are often used: is not → isn’t, has not → hasn’t, did not → didn’t, etc.
5. Emphasis
Do is often used to give emphasis in positive statements.
Examples:
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I do want to come!
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He does like the movie, really!
List of Auxiliary Verbs in English
| Auxiliary Type | Verb Forms |
|---|---|
| Be | am, is, are, was, were, be, being, been |
| Have | have, has, had |
| Do | do, does, did |
| Modals | can, could, may, might, shall, should, will, would, must, ought to, need to, used to |
Note: Some expressions like “have to, be going to, and be able to” also function like modals in structure, but grammatically they are not pure modal verbs.
Auxiliary Verbs vs. Main Verbs – What’s the Difference?
A main verb (also called a lexical verb) shows the main action or state in a sentence. It carries meaning by itself.
An auxiliary verb helps the main verb and does not carry full meaning alone. It provides grammatical support such as showing tense or forming a question.
Sometimes, verbs like be, have, and do can act as either auxiliary or main verbs, depending on the sentence.
| Verb | As Auxiliary Verb | As Main Verb |
|---|---|---|
| be | She is running. | She is a teacher. (shows state) |
| have | We have finished. | We have a car. (shows possession) |
| do | Do you know her? | I do my homework. (action verb) |
Key Rule: If a verb comes before another verb (usually the base or past participle), it’s likely an auxiliary verb. If it stands alone with its own meaning, it’s the main verb.
Common Mistakes with Auxiliary Verbs
English learners often make small but common errors when using auxiliary verbs. Understanding these mistakes will help you use auxiliaries more accurately in both writing and conversation.
1. Using the Wrong Auxiliary in Negative Sentences
Incorrect: He don’t like coffee.
Correct: He doesn’t like coffee.
Tip: In the present simple tense, use do/does for negatives. “He” takes doesn’t, not “don’t.”
2. Forgetting the Auxiliary in Questions
Incorrect: You going to the party?
Correct: Are you going to the party?
Tip: In questions, always include the correct auxiliary verb at the beginning.
3. Using Modals with “to”
Incorrect: She can to drive.
Correct: She can drive.
Tip: Modal verbs like can, should, must, might are followed by the base form of the verb without “to.”
4. Repeating Auxiliary Verbs
Incorrect: Did you went to school yesterday?
Correct: Did you go to school yesterday?
Tip: When you use did (past tense auxiliary), the main verb stays in its base form: go, not went.
5. Not Using Auxiliary in Short Answers
Incorrect: Do you like pizza? – Yes, I.
Correct: Do you like pizza? – Yes, I do.
Tip: Always repeat the auxiliary verb in short answers (do, did, can, etc.).
Auxiliary Verbs Quiz
1. She ____ watching a movie when I called.
a) has
b) is
c) was
2. They ____ finished their homework before dinner.
a) do
b) have
c) are
3. ____ you like some tea?
a) Do
b) Are
c) Have
4. He ____ not know the answer to the question.
a) does
b) has
c) is
5. We ____ going to the market now.
a) do
b) are
c) have
6. I ____ never seen snow before this trip.
a) am
b) have
c) do
7. Why ____ she crying?
a) does
b) is
c) has
8. My brother ____ play the guitar, but not the piano.
a) can
b) is
c) likes
9. You ____ study harder if you want to pass.
a) have
b) should
c) are
10. We ____ waiting for the bus when it started to rain.
a) are
b) have
c) were
Quiz Answers
1) was
2) have
3) Do
4) does
5) are
6) have
7) is
8) can
9) should
10) were
