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Chapter 16: Help for English Language Learners

16.6 Modal Auxiliaries


By the end of this section, you will be able to:

  • Define and identify modal auxiliaries.
  • Learn how and when to use modal auxiliaries.

We all need to express our moods and emotions, both in writing and in our everyday life. We do this by using modal auxiliaries.


Modal auxiliaries are a type of helping verb that are used only with a main verb to help express its mood.

The following is the basic formula for using a modal auxiliary:

Subject + modal auxiliary + main verb
James may call

There are ten main modal auxiliaries in English.

Table 4.11 Modal Auxiliaries

Modal Auxiliary Use Modal Auxiliary + Main Verb
can Expresses an ability or possibility I can lift this forty-pound box. (ability)
We can embrace green sources of energy. (possibility)
could Expresses an ability in the past; a present possibility; a past or future permission I could beat you at chess when we were kids. (past ability)
We could bake a pie! (present possibility)
Could we pick some flowers from the garden? (future permission)
may Expresses uncertain future action; permission; ask a yes-no question I may attend the concert. (uncertain future action)
You may begin the exam. (permission)
May I attend the concert? (yes-no questions)
might Expresses uncertain future action I might attend the concert (uncertain future action—same as may)
shall Expresses intended future action I shall go to the opera. (intended future action)
should Expresses obligation; ask if an obligation exists I should mail my RSVP. (obligation, same as ought to)
Should I call my mother? (asking if an obligation exists)
will Expresses intended future action; ask a favor; ask for information I will get an A in this class. (intended future action)
Will you buy me some chocolate? (favor)
Will you be finished soon? (information)
would States a preference; request a choice politely; explain an action; introduce habitual past actions I would like the steak, please. (preference)
Would you like to have breakfast in bed? (request a choice politely)
I would go with you if I didn’t have to babysit tonight. (explain an action)
He would write to me every week when we were dating. (habitual past action)
must Expresses obligation We must be on time for class.
ought to Expresses obligation I ought to mail my RSVP. (obligation, same as may)


Use the following format to form a yes-no question with a modal auxiliary:

Modal auxiliary + subject + main verb
Should I drive?


  1. Using an infinitive instead of a base verb after a modal Incorrect: I can to move this heavy table. Correct: I can move this heavy table.
  2. Using a gerund instead of an infinitive or a base verb after a modal Incorrect: I could moving to the United States. Correct: I could move to the United States.
  3. Using two modals in a row Incorrect: I should must renew my passport. Correct: I must renew my passport. Correct: I should renew my passport.
  4. Leaving out a modal Incorrect: I renew my passport. Correct: I must renew my passport.


In the previous section, we defined present perfect verb tense as describing a continuing situation or something that has just happened.

subject + has or have + past participle
I have helped
He has helped

Remember, when a sentence contains a modal auxiliary before the verb, the helping verb is always have.

subject + modal auxiliary + have + past participle
I could have helped
He could have helped
He might have helped
He may have helped
He should have helped

Be aware of the following common errors when using modal auxiliaries in the present perfect tense:

  1. Using had instead of have Incorrect: Jamie would had attended the party, but he was sick. Correct:Jamie would have attended the party, but he was sick.
  2. Leaving out have Incorrect: Jamie would attended the party, but he was sick. Correct: Jamie would have attended the party, but he was sick.


  • The basic formula for using a modal auxiliary is
    subject + modal auxiliary + main verb
  • There are ten main modal auxiliaries in English: can, could, may, might, shall, should, will, would, must, and ought to.
  • The four common types of errors when using modals include the following: using an infinitive instead of a base verb after a modal, using a gerund instead of an infinitive or a base verb after a modal, using two modals in a row, and leaving out a modal.
  • In the present perfect tense, when a sentence has a modal auxiliary before the verb, the helping verb is always have.
  • The two common errors when using modals in the present perfect tense include using had instead of have and leaving out have.


1. Edit the following paragraph by correcting the common modal auxiliary errors.

I may to go to France on vacation next summer. I shall might visit the Palace of Versailles. I would to drive around the countryside. I could imagining myself living there; however, I will not move to France because my family should miss me very much.

2. On a separate sheet of paper, complete the following sentences by changing the given verb form to a modal auxiliary in present perfect tense.

  • The man ________ (laugh).
  • The frogs ________ (croak).
  • My writing teacher ________ (smile).
  • The audience ________ (cheer) all night.
  • My best friend ________ (giggled).


On a separate sheet of paper, write ten original sentences using modal auxiliaries.


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