Grammar Rules

Auxiliary (or Helping) Verbs

Auxiliary (or Helping) verbs are used together with a main verb to show the verb's tense or to form a negative or question. The most common auxiliary verbs are have, be, and do.
  1. Does Sam write all his own reports?
  2. The secretaries haven't written all the letters yet.
  3. Terry is writing an e-mail to a client at the moment.

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Auxiliary verbs, also known as helping verbs, add functional or grammatical meaning to the clauses in which they appear. They perform their functions in several different ways:
  • By expressing tense ( providing a time reference, i.e. past, present, or future)
  • Grammatical aspect (expresses how verb relates to the flow of time)
  • Modality (quantifies verbs)
  • Voice (describes the relationship between the action expressed by the verb and the participants identified by the verb’s subject, object, etc.)
  • Adds emphasis to a sentence
Auxiliary verbs almost always appear together with a main verb, and though there are only a few of them, they are among the most frequently occurring verbs in the English language.

How to Identify an Auxiliary Verb

You probably know that every sentence has at least one verb in it. There are two main types of verbs. Action verbs are used to depict activities that are doable, and linking verbs are used to describe conditions. Both action verbs and linking verbs can accompany auxiliary verbs including the three main ones: do, be, and have. Sometimes actions or conditions occur only one time and then they’re over. It’s at times like these that some of the same verbs that are used as auxiliary verbs are instead used as action or linking verbs. In this example, we see the word “is”. This is one of the most common auxiliary verbs, but because it stands alone here, it is not functioning as an auxiliary verb. Jerry slammed the car door on his thumb. He is in horrible pain. “Is” is a linking verb in this sentence. Because it stands alone, it is not an auxiliary verb. At other times, an action or condition is ongoing, happening predictably, or occurring in relationship to another event or set of events. In these cases, single-word verbs like is are not accurately capable of describing what happened, so phrases that include auxiliary verbs are used instead. These can be made up of anywhere from two to four words. A main verb, also known as a base verb, indicates the kind of action or condition taking place. An auxiliary or helping verb accompanies the main verb and conveys other nuances that help the reader gain specific insight into the event that is taking place. Read the following sentences and explanations to gain greater insight into how auxiliary verbs work.
  1. Jerry caught his thumb in the car door as coffee spilled from his cup onto his favorite shirt.
  2. Jerry is always spilling things.
  3. Since Jerry is also accident prone, he should have been drinking coffee from a mug with a lid, which would not have spilled on his favorite shirt.
In sentence one, caught and spilled, single-word verbs, describe quick, one-time actions of both Jerry and his messy coffee. This sentence does not contain an auxiliary verb. Since Jerry often has unfortunate accidents, is spilling communicates the frequency of his clumsy actions in sentence two. In sentence three, the auxiliary verbs that make up should have been drinking and would have stained express time relationships as well as an evaluation of Jerry’s actions.

Three Common Auxiliary Verbs

There are just three common auxiliary verbs:
  • Have
  • Do
  • Be
In this section, we’ll take a closer look at how these common verbs work, plus you’ll see some examples.


“Have” is a very important verb that can stand alone in all its tenses, including has, have, having, had, and hadn’t or had not. It is usually used to denote ownership, and it can also be used to discuss ability or describe appearance. “Have” is also a very popular substitute for the verbs “eat” and “drink.” For example: “Let’s have dinner.” When used as an auxiliary verb, have is always teamed up with another verb to create a complete verb phrase, making it easy to differentiate between uses. You can see the difference in the sentences below:
  • Jerry has a large coffee stain on his shirt. → Has = action verb
  • Jerry has bought a new shirt to replace the one that was ruined earlier. → Has = auxiliary verb; bought is a past participle that competes the verb phrase.
  • Jerry should have been more careful! → Have = auxiliary verb; phrase “should have been” expresses time and evaluates Jerry’s actions.


“Do” can be used as an action verb that stands alone in all its tenses, including to do, do, does, done, did and didn’t, doesn’t or did not . When used as an auxiliary verb, do is always paired up with another verb to create a complete verb phrase. In some cases, it is used to add emphasis: “I did put the garbage out!” Do is often used to form questions and negated clauses. It is also used in elliptical sentences, where the main verb is understood and is omitted as a result. For example: “He plays piano well, doesn’t he?” or “They all had dinner, but I didn’t.”
  • Because he spills things so often, Jerry does more laundry than most people.  Does = action verb
  • Jerry didn’t put his coffee in a cup with a lid.  Didn’t = auxiliary verb
  • Jerry doesn’t always spill things, but it happens a lot.  Doesn’t = auxiliary verb


“Be” or “to be” is an important verb that has a multitude of uses in English. It can be used as an action verb that stands alone in all its tenses including be, to be, been, am, are, is, was, were, wasn’t, was not aren’t, are not, weren’t and were not. When used as an auxiliary verb, be is always paired with another verb to create a complete verb phrase. It can be singular or plural, present or past. Negative sentences are formed by adding the word “not”.
  • Jerry is messy.  Is = action verb
  • Although he is always complaining about his accidents, Jerry fails to pay attention.  is = auxiliary verb
  • Jerry is going to be doing extra laundry for the rest of his life.  to be = auxiliary verb

Modal Auxiliary Verbs

In addition to the three main auxiliary verbs, have, do, and be, there are additional auxiliary verbs. These are called modal auxiliary verbs, and they never change form. A complete list of modal auxiliary verbs follows:
  • Can
  • Could
  • May
  • Might
  • Must
  • Ought to
  • Shall
  • Should
  • Will
  • Would

Auxiliary Verb Examples

Here are some examples of auxiliary verbs and verb phrases. In the examples below, the verb phrase is italicized and the auxiliary verb is in bold.
  1. Jessica is taking John to the airport.
  2. If he doesn’t arrive on time, he’ll have to take a later flight.
  3. Unfortunately, our dinner has been eaten by the dog.
  4. I have purchased a new pair of shoes to replace the ones that were lost in my luggage.
  5. We hope you don’t have an accident on your way to school.
  6. She was baking a pie for dessert.
  7. Dad has been working hard all day.
  8. The bed was made as soon as I got up.
  9. Sarah doesn’t ski or roller skate.
  10. Did Matthew bring coffee?

Auxiliary Verb Exercises

Fill in the blank with the correct auxiliary verb from the choices presented:
  1. What ________________ the kids doing when you last saw them? (was, were, are, did, been)
  2. Carla ________________ always wanted to try skydiving. (was, doesn’t, has, is, have)
  3. Where __________________ you go on your summer vacation? (were, been, are, did, does)
  4. Why do you think she __________ call you like she said she would? (didn’t, is, hasn’t, has been, have)
  5. Mary _____________ going to be upset when she hears what happened. (will, don’t, is, didn’t, has)
  6. Jeremy _____________ want to go to the movies; he wants to stay home instead. (doesn’t, isn’t, wasn’t, hasn’t, was not)
  7. I _________________ appreciate his jokes. They weren’t funny. (did, have, been, didn’t, haven’t)
  8. I really like fish but I _______________ care for meat. (weren’t, been, don’t, is, was)
  9. Where _____________ you going when I saw you last night? (were, was, is, do, did)
  10. Tara ________________ called yet; she’s late as usual. (are, were, has, hasn’t, wouldn’t)
Answers: 1 – were, 2 – has, 3 – did, 4 – didn’t, 5 – is, 6 – doesn’t, 7 – didn’t, 8 – don’t, 9 – were, 10 – hasn’t