What Are Auxiliary Verbs? Definition and Examples

Have you ever wondered what makes English sentences like “She is running” or “They have finished” tick? The secret lies in auxiliary verbs—also known as helping verbs.

These small but mighty words don’t get much attention, but they’re everywhere. Without them, we couldn’t form questions, talk about the past, express possibility, or build complex sentences. In fact, even simple expressions like “I do like it” wouldn’t exist without auxiliary verbs.

If you’ve ever struggled with when to use do, have, is, or can, you’re not alone. English learners often find these verbs confusing because they change form depending on the tense, the subject, and the sentence type (question, negative, passive, etc.).

In this complete, no-fluff guide, I’ll walk you through:

• What auxiliary verbs are and why they matter
• The difference between primary and modal auxiliaries
• How they’re used to form tenses, ask questions, and express mood
• Common mistakes learners make—and how to fix them
• Real examples you can relate to and remember

Let’s break it all down, step by step.

What Are Auxiliary Verbs?

An auxiliary verb (also called a helping verb) is a verb that supports the main verb in a sentence. It gives us extra information about tense, mood, voice, or condition.

Think of it like a sidekick. The main verb does the main action, but the auxiliary verb helps it do the job properly.

Here:

• “is” = auxiliary verb
• “running” = main verb (action)

Together, they show what’s happening right now—that’s present continuous tense. Without “is,” the sentence would be incomplete.

Why Do We Need Auxiliary Verbs?

Auxiliary verbs are the glue that holds English sentences together. They help:

• Form different tenses

• Create questions and negatives

• Build passive voice

• Express possibility, obligation, or ability

In short, they’re everywhere, even if you haven’t noticed them.

The Three Primary Auxiliary Verbs

These are the core helping verbs you’ll see most often: be, have, and do. They’re the backbone of English grammar and play a major role in forming different verb tenses, passive voice, questions, and more.

Let’s break each one down with simple explanations and plenty of examples.

1. BE – The Verb That Shows “What’s Happening”

The verb “be” helps form continuous (progressive) tenses and the passive voice.

Common Forms:

am, is, are, was, were, being, been

Uses of “Be”:

• Continuous Tenses → She is working.
• Passive Voice → The project was finished yesterday.

2. HAVE – The Verb That Talks About “What’s Done”

The verb “have” helps form perfect tenses, which show that something happened before now or before another action.

Common Forms:

have, has, had

Uses of “Have”:

• Present Perfect → I have eaten.
• Past Perfect → She had left before I arrived.

3. DO – The Verb That Helps You Ask & Deny

The verb “do” helps form questions, negatives, and sometimes adds emphasis in the present and past simple tenses.

Common Forms:

do, does, did

Uses of “Do”:

• Making Questions → Do you like music?
• Making Negatives → She doesn’t eat meat.
• Adding Emphasis → I do love that movie!

Difference Between Auxiliary Verbs and Main Verbs

One of the biggest sources of confusion for learners is telling the difference between auxiliary verbs and main verbs—especially since some words (like be, have, and do) can be used as either.

Let’s break it down clearly.

Auxiliary Verbs (Helping Verbs)

These don’t stand alone. They support the main verb to build tense, form questions, negatives, etc.

Main Verbs

These carry the main meaning of the action or state.

How to Tell the Difference:

So always ask: Is this verb carrying the action, or helping another verb?

A Quick Test: Can You Spot the Auxiliary?

Which word is the auxiliary verb?

“We are watching a movie tonight.”

Answer: “are” (It helps form the present continuous tense)

Modal Auxiliary Verbs

Modal auxiliary verbs are like little power words that help us express mood, attitude, or intention. They don’t show action, but they change the way the main verb works.

We use modals to talk about:

• Possibility
• Ability
• Permission
• Advice
• Necessity
• Predictions
• Intentions
• Hypotheticals

Modal verbs are always followed by the base form of the main verb (no -s, -ed, or -ing). You never say “He can swims” or “She musted go.”

Common Modals (with meanings):

Semi-Auxiliary Verbs

These aren’t pure auxiliaries, but they function similarly by helping the main verb. Examples include:

• Be going to → I am going to travel.
• Have to → She has to finish it.
• Need to → You need to study more.

They’re often called semi-modals and are very common in everyday English.

How Auxiliary Verbs Work in Sentences

Auxiliary verbs don’t just sit there—they do the heavy lifting when you want to form tenses, ask questions, make negatives, use the passive voice, or add emphasis.

Let’s explore how.

Forming Tenses

Auxiliary verbs help build different verb tenses. Without them, we couldn’t show when something happened, or if it’s still happening.

Note:

• Use “be” for continuous actions
• Use “have” for perfect tenses
• Combine them when needed (like have been doing)

Creating the Passive Voice

In the passive voice, the focus shifts from who does something to what is done.

Examples:

• Active: The chef cooked the meal.
• Passive: The meal was cooked by the chef.
• Active: They are cleaning the room.
• Passive: The room is being cleaned.

You still need to match “be” to the tense of the sentence:

• is/are → present
• was/were → past
• has been/have been → present perfect
• will be → future

Asking Questions and Making Negatives

Auxiliary verbs are essential in question formation and negative sentences—especially in simple tenses.

Using do/does/did:

Using be/have:

Common Question Words with Auxiliaries:

• Where do you live?
• Why has she gone?
• What are they doing?

Question Tags

Question tags are those little additions at the end of a sentence, often used for checking or confirming.

The auxiliary verb in the main sentence is mirrored in the question tag—just flipped to positive/negative.

Subject–Auxiliary Inversion

In questions, we often switch the position of the subject and auxiliary verb.

This is called inversion, and it happens with:

• Questions
• Conditionals (Had I known…)
• Emphatic constructions (So did I!)

Adding Emphasis

Auxiliary verbs can be used to stress a point, especially in conversation or writing where tone matters.

Note: Only do/does/did are used for emphasis in this way—and only in affirmative sentences.

Let’s Look at One Sentence in Full

Breakdown:

• has been = helping verbs forming present perfect continuous
• working = main verb (action)
• does = auxiliary used for emphasis
• enjoy = base form of verb after “does”

That one sentence includes all the main types of auxiliaries!

Don’t forget contractions in casual English

In spoken or informal writing, we often contract auxiliary verbs:

Contractions make your English sound more natural and fluent.

Common Mistakes Learners Make (and How to Fix Them)

Let’s fix some frequent errors learners make when using auxiliary verbs. Catching these early will boost your confidence big time.

Using the Wrong Auxiliary with Tense

Always match the subject and verb form correctly (singular/plural, tense, etc.).

Forgetting the Auxiliary in Questions

Even in casual conversation, questions in English usually need an auxiliary (unless using intonation alone informally).

Mixing Up Modal and Main Verbs

Modal auxiliaries are always followed by the base form of the verb—no “to”!

Double Negatives with Auxiliaries

Stick to one negative in standard English.

Practice Quiz (with answers below – no cheating!)

Fill in the blanks with the correct auxiliary verb:

1. She ___ playing the piano beautifully.
2. I ___ never seen that movie before.
3. ___ you help me with this?
4. He ___ not like spicy food.
5. They ___ been working since morning.
6. You ___ take your umbrella. It looks like rain.
7. What ___ she doing at that time?
8. We ___ to leave early yesterday.
9. You ___ be quiet in the library.
10. I ___ call him now if you want.

Answers:

1. is
2. have
3. Can
4. does
5. have
6. should
7. was
8. had
9. must
10. can

Summary & Final Thoughts

Auxiliary verbs are small but powerful. They’re the backbone of English grammar when it comes to forming:

• Questions
• Negatives
• Tenses
• Passive voice
• Emphasis
• And much more

By mastering auxiliary verbs like be, have, do, and the modal verbs, you’ll gain much more control over your English—and sound more natural and fluent doing it.