Auxiliary verb: Meaning, types, list and examples

An auxiliary verb is one of the first grammar concepts English learners encounter, yet it is often misunderstood because the same few words, such as do, have, and will, appear in many different sentence patterns. Understanding how these words work is essential for forming questions, negatives, tenses, and the passive voice correctly.

This article explains the meaning and function of auxiliaries, the difference between primary and modal auxiliaries, a list of common examples, and exercises with answers to help you check your understanding.

Auxiliary verb meaning

Definition

An auxiliary verb, also called a helping verb, is a verb used together with a main verb to build a complete verb phrase. It does not usually carry the main meaning of the sentence on its own; instead, it adds grammatical information such as tense, aspect, voice, or mood.

Example: She is working. – “is” is the auxiliary verb, and “working” is the main verb.

Why auxiliary verbs matter

Auxiliaries are involved in almost every part of English sentence structure: forming continuous and perfect tenses, making questions, forming negatives, building the passive voice, and adding modal meaning such as ability, possibility, or obligation.

Types of auxiliary verbs

English auxiliary verbs fall into two main groups: primary auxiliaries and modal auxiliaries.

Primary auxiliary verbs

The primary auxiliaries are be, do, and have. Each can also function as a main verb on its own, which is part of what makes them confusing for learners.

• be: used to form continuous tenses and the passive voice. She is reading. The letter was sent yesterday.
• do: used to form questions and negatives in the simple present and simple past, as well as for emphasis. Do you like coffee? I did not see him. I do understand.
• have: used to form perfect tenses. They have finished the report. She had already left.

Modal auxiliary verbs

Modal auxiliaries add meaning related to ability, permission, possibility, necessity, or advice. Unlike primary auxiliaries, they cannot function as main verbs and are always followed by the base form of the main verb.

Auxiliary verb list

The table below provides a quick list of auxiliaries, separated into primary and modal auxiliaries, with a short note on their typical uses.

Auxiliary verb examples by function

Forming tenses

• Present continuous: They are studying English.
• Present perfect: We have visited that museum before.
• Past continuous: He was driving when it started to rain.

Forming questions

• Do you speak French?
• Have you finished your homework?
• Can she swim?

Forming negatives

• I do not agree with that.
• She has not called yet.
• They cannot attend the meeting.

Forming the passive voice

• The cake was baked by my mother.
• This report has been reviewed twice.
• The window will be repaired tomorrow.

Adding modal meaning

• You must wear a seatbelt. (obligation)
• It might rain later. (possibility)
• You should see a doctor. (advice)

An auxiliary verb versus a main verb: How to tell them apart

Sometimes the same word can be either an auxiliary verb or a main verb, depending on the sentence. be, do and have are the words most often confused this way.

• She is a teacher. – “is” is the main verb here, describing her identity.
• She is teaching now. – “is” is an auxiliary verb here, helping form the continuous tense with “teaching.”
• I have a car. – “have” is the main verb, meaning “own.”
• I have finished my work. – “have” is an auxiliary verb here, forming the present perfect with “finished.”

A simple test is to check whether the word is followed by another verb form (such as an -ing form or a past participle). If it is, the first word is usually functioning as an auxiliary verb.

Common mistakes with auxiliary 

• Adding an unnecessary auxiliary: writing I am agree with you instead of I agree with you, confusing the auxiliary “be” with a verb that does not require it in the simple present.
• Omitting the auxiliary in questions: writing You like coffee? as a complete question instead of Do you like coffee?
• Using the wrong form after a modal: writing She can to swim instead of She can swim, since modals are always followed by the base form without “to.”
• Confusing “has” and “have” with subject – verb agreement: writing She have finished instead of She has finished.
• Using double negatives with “do not”: writing I don’t know nothing instead of I don’t know anything, since standard English generally avoids using two negative words in the same clause.

Auxiliary exercise with answers

Use the following auxiliary verb exercise to check what you have learned.

Exercise 1: Choose the correct auxiliary verb

1. ______ you like tea or coffee? (Do / Are)
2. She ______ finished her homework already. (has / is)
3. They ______ playing football when it started to rain. (were / have)
4. You ______ wear a helmet when riding a motorbike. (must / do)

Sample Answers: 1. Do – 2. has – 3. were – 4. must

Exercise 2: Identify the auxiliary verb

1. He is watching TV right now. → auxiliary verb: is
2. We have never been to Japan. → auxiliary verb: have
3. Does she work on weekends? → auxiliary verb: Does

Exercise 3: Correct the mistake

1. I am agree with your idea. → correct to I agree with your idea.
2. She can to drive a car. → correct to She can drive a car.
3. You like this song? → correct to Do you like this song?

Auxiliary verbs in negative contractions

In everyday speech and informal writing, auxiliary verbs are often shortened using contractions, and learners sometimes struggle to recognize the auxiliary verb once it is contracted. Common contractions include don’t (do not), doesn’t (does not), isn’t (is not), aren’t (are not), haven’t (have not), hasn’t (has not), can’t (cannot), won’t (will not) and shouldn’t (should not). Recognizing these forms is useful both for listening comprehension and for writing at an appropriate level of formality, since contractions are common in conversation but are usually avoided in formal academic writing.

Using an auxiliary worksheet for practice

A structured auxiliary verb worksheet typically mixes the exercise types above: multiple choice, identification, and error correction, sometimes organized by tense or by primary and modal auxiliaries. Working through a worksheet regularly, rather than only reading the rules, helps you notice patterns such as which auxiliary goes with which tense and reduces the kinds of mistakes listed above over time.

An auxiliary supports the main verb in a sentence to form tenses, questions, negatives, the passive voice, and modal meaning. Learning the difference between primary auxiliaries (be, do, have) and modal auxiliaries (can, will, must, and others), along with practicing through exercises, helps you use them accurately in both speaking and writing.

See also: Stative verb: Meaning, use and exercises

Frequently asked questions

What is the difference between a primary auxiliary verb and a modal auxiliary verb?

Primary auxiliaries (be, do, have) can also function as main verbs on their own and are used to form tenses, questions, negatives, and the passive voice. Modal auxiliaries (can, could, will, would, shall, should, may, might, must) cannot function as main verbs and are always followed by the base form of the main verb, adding meanings such as ability, possibility, or obligation.

Can a sentence have more than one auxiliary verb?

Yes. Sentences with the present perfect continuous or the passive voice in a perfect tense often combine two auxiliaries, for example, She has been working here for five years, where “has” and “been” both support the main verb “working.”

How can I practice auxiliary verbs effectively?

Working through exercises that mix multiple choice, identification, and error correction, similar to an auxiliary worksheet, helps you see how the same auxiliary behaves differently across tenses and sentence types. Reviewing your own writing for missing or unnecessary auxiliaries is also a practical way to reinforce the rules over time.

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