Modal Verbs

Breaking Down Modal Auxiliary Verb

Modal Auxiliary Verb (also called Modal Verb, or Modal Auxiliary) is a type of verbOpens in new window that is combined with another verb to express certainty, ability, intention, necessity, obligation, opinion, permission, possibility, probability, prohibition, and speculation etc.

The Modal Verbs include:
cancould will
The semi-modals include:
ought toneed tohave to, and used to

These verbs indicate the attitude towards what we are saying.

Modal verbs cannot stand alone; they are usually combined with a verb group to convey important nuances of meaning, such as wishes, permission or prohibition, intent or willingness, obligation or necessity, ability or possibility, probability, and certainty.

Modality and Associated Modal Verb

The chart below outlines which Modal verbs are used to express a particular concept.

ModalityModal VerbMeaning (and Examples)
    Can and could imply ability. Could, however, is the past tense of can. E.g.

  • “If Andy can swim, he will accept the swimming invitation.
  • Gretchen could draw beautifully when she was a child but now she says she can’t draw at all.
    May and might are used to express possibility; both are used where the possibility exists as far as you know, with might often suggesting a lower probability. e.g.,

  • “I may attend the wedding if I can find my favorite shoe” (suggests that you do want to attend the wedding) whereas;
  • “I might attend the wedding” (suggests that you don’t)
    Should and Must are used to express suggestion or a sense of duty. Note the sense of obligation in these two sentences:

  • “Andy should study harder if he wants to get good grades”
  • “Andy must study harder to improve his grades, according to his teacher.”
    Will and Would may be used to express willingness. E.g.

  • “I will be happy to help with the dishes.”
    Sometimes, would may express repeated past actions or habits. E.g.

  • “Every Saturday he would work on his farm”)

Observe the meanings in the following sentences where the modal verbs indicate varying degrees of certainty.

Shades of Meaning Degrees of Certainty
  • It might rain tonight
  • She could have done it
  • It may rain tonight
  • She may have done it
  • It will rain tonight
  • She must have done it

The meaning of modal verbs varies with the context. For instance, must, usually denotes obligation or compulsion (e.g., she must go), it has a completely different meaning in another expression like she must be in love, in which it denotes a tone of certainty on the part of the speaker.

Likewise, may in a sentence like, You may go, denotes permission, whereas You may do well on this test indicates possibility.

Characteristics of the Modal Verbs

The modal verbs are members of a larger set of auxiliary verbs Be and Have, and share some properties with auxiliary verbs, but in addition, they have formal features of their own:

1.  They do not co–occur, i.e., there is no such phrase as:

  • will can come, may shall be, etc.

Though in some dialects there are very limited possibilities of co-occurrence such as might could.

2.  The modal auxiliaries cannot stand alone. They always go with a main verb that is expressed or understood:

  • Nicole can play the violin. (main verb, play, is expressed.)
  • I can too, (main verb is understood, i.e. it means, ‘I can play the violin, too’)
  • You should come again. (Main verb is expressed)
  • Should I? (Main verb is understood, i.e. it means, ‘Should I come again?’)

3.  The modal auxiliaries do not change forms according to the person or number of the subject. As a result, they have no -s forms for their third person singular, i.e.,

  • I should be very careful.
  • We/They should be very careful while driving.
  • He/she should obey her parents.
  • You should be careful while talking with elders.

Notice that the modal verb (should) remains unchanged across the various person and number of the subject.

4.  The modal auxiliaries do not take the infinitive form. We cannot use to may, to can, to must, etc. or canning; there is no such construction as, I hope to can come tomorrow.

5.  The past participle or the third form of a verb is only possible when have is used after the modal, as:

  • The passengers might have started their journey by now.
  • He may have reached the station.

6.  They have no imperatives; as in: Can be here! Must come now!

7.  All the modals basically indicate a present or future action, as:

  • He would return soon. (He is expected to return in the near future.)
  • He could be appointed as a manager tomorrow.

8.  Particularly, must, has no past tense form, although others such as could, should, might, etc. do have; of those forms, only could is used to refer to past time (though all may occur in reported speech).

9.  They are followed by infinitive form of the main verb. i.e. may I borrow your English text book?

Uses of the Modal Verbs

Modal verbs are not limited to one particular use. Most of them can be used to express several other concepts. Here, we look out the uses of the modal verbs in pairs.

What's this?
Modal VerbMeaning (and Examples)

can (present)

indicates ability, or possibility in the present

  • I can run a kilometre in three minutes.
  • Yes, I can come tonight.

could (past)

indicates ability, or possibility in the past

  • I could do that when I was younger.
  • You could be sacked if you keep getting drunk.
Modal VerbMeaning (and Examples)

may (present)

indicates permission

  • may I use some of your reading materials? yes you may (I permit you)
  • may I leave class early? yes you may (I give you permission)
Modal VerbMeaning (and Examples)

may (present)

expresses possibility

  • I may complete the assignment today.
  • She may be my advisor next semester.

might (past)

expresses possibility

  • She might be my advisor next semester.
  • I might complete the assignment today.
Modal VerbMeaning (and Examples)

should (present tense)

indicates advice, recommendation, and suggestion

  • You really shouldn't do that.
  • You look tired, you should take your leave.
Modal VerbMeaning (and Examples)

must (present tense)

indicates necessity, and obligation

  • Pedestrians must use the pedestrian bridges.
  • Students must pay their university fees before they are allowed to write exams.

Note that the past form of must is had to. See examples below:

  • My class teacher said I had to submit my assignment by today.
  • I could not attend the party because I had to study for my exams.

Future Tense — Will/shall and would/should are also used to form future tenses.

Modal VerbMeaning (and Example)

will (present tense)

expresses something that takes place in the future

  • I will call you when I get to my apartment.

would (past tense)

expresses something that was in the future at that point in time

  • Grandma would not go out on Tuesdays because of her bible studies.


expresses something that is expected to take place in the future

  • The students shall be sitting for their ESL come next week.
  • The students knew they should sit for their ESL next week.
Semi Modals

There are other verbs that have a similar meaning to modals but are followed by “to” and the infinitive form of the main verb.

ought to

indicates obligation, advice or suggestion

  • We ought to help the needy.
  • You ought to pay your fees.

have to/had to

indicates necessity, obligation

  • I have to be punctual.
  • We have to obey traffic rules.

need to

indicates necessity

  • My daughter is hardworking. I need to support her in every way.
  • We need to see the principal by 12 noon.