Modal Auxiliary Verbs: Definition, Uses & Examples

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  • 0:00 What Are Modal…
  • 0:35 Examples of Modal…
  • 1:05 Indicating Past Tense
  • 2:02 Examples
  • 2:42 Lesson Summary
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Lesson Transcript
Instructor: Margaret Stone

Margaret has taught both college and high school English and has a master's degree in English.

Modal auxiliary verbs are easy to use because they never change form or tense. These verbs are full of possibilities! In fact, possibility is just one thing modal auxiliary verbs can show; they can also indicate necessity, capability, or willingness.

What Are Modal Auxiliary Verbs?

Modal auxiliary verbs are used to show a necessity, capability, willingness, or possibility. Unlike most verbs, there is only one form of these verbs. Typically, verb forms change to indicate whether the sentence's structure is singular or plural. Most verbs also indicate whether something happened in the past, present, or future. This is not the case with most modal auxiliary verbs, which makes them simpler to understand and use correctly.

Examples of Modal Auxiliary Verbs

So, now that we understand the purpose of modal auxiliary verbs, let's take a look at some of the common ones you may see in writing. The modal auxiliary verbs include:

  • Can
  • Could
  • May
  • Might
  • Must
  • Ought
  • Shall
  • Should
  • Will
  • Would

Modal Auxiliary Verbs

It's important to note that these verbs can also indicate the negative: could not, may not, should not, etc.

Indicating Past Tense

Since modal auxiliary verbs do not have a past tense form, we can use the modal auxiliary along with the word 'have' and a past participle. Past participles typically end in -d, -ed, -n, or -en, creating the past tense 'wished, looked, taken,' and so forth. Let's take a look at an example in the present tense.

Let's say I'm at the store in the produce section:

  • I should buy another pound of potatoes.

When I come home from the grocery store and realize that my potato bin is empty, I will use past tense. To change this sentence, which currently uses the modal auxiliary verb 'should,' to past tense, we would follow the rule we just discussed.

  • I should have bought another pound of potatoes.

Notice that the past tense verb 'buy' changes its spelling to become past tense, as past tense verbs often do. Also, to put this sentence in the past tense, we have the addition of the word 'have.'


Look at the way these sentences indicate a possibility, necessity, capability, or willingness. The modal auxiliary verb is bold in these sentences.

  • I can help you paint.
  • Anthony will help you paint today.
  • Leslie should help you paint after school.
  • David could help you paint, but he doesn't want to stand on the ladder.

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