The mechanics of modal auxiliary verbs

Modal auxiliary verbs are used to express different moods. In English grammar, this function is regarded as modality. Some of the modal auxiliary verbs in English are can, could, may, might, shall, should, will, would, ought to and must. This treatise will discuss how these verbs are used to indicate ability, permission, possibility, wishes, and hope, among other functions.


Can is used to express the ability to do something, as in:

I can lift the table.

Douglas cannot speak Spanish.

The general reader should take note that using ‘can’ alongside ‘be able to’ is tautologous. As such:

The pupils can be able to read (non-standard).

The pupils can read (standard).

The pupils are able to read (standard).

Could is the past tense of can. Hence, we use could to express general ability in the past thus:

Back in the day, I could travel to London twice a month.

In addition, both ‘can’ and ‘could’ are used to give instructions or make requests, although could is more polite.

Read Also: The uses and functions of auxiliary verbs

Auxiliary verbs

Stella, can you do the laundry at noon?

Stella, could you do the laundry at noon (more polite)?

Again, ‘can’ and ‘could’ are used to request permission thus:

Madam, can we go to the conveniences?

Madam, could we go to the conveniences (more polite)?

Note, however, that, in the foregoing context, only ‘can’ should be used to give permission.

Pupils: Madam, can/could we go to the conveniences?

Teacher: Yes, you can (standard).

Yes, you could (non-standard).


Although might is the past tense of may, both modal verbs can be deployed to express the possibility of an occurrence, as in:

She may travel to the Seychelles next year.

I might lend him £500.

Although ‘might’ should be used in reported speeches:

Sandra said she might travel to the Seychelles the following year (standard).

Furthermore, like can/could, ‘may/might’ are used to seek permission. Nonetheless, the latter pair is more formal than the former pair.

May I leave these premises now?

Might I leave these premises now (more polite)?

In both cases, the appropriate response is:

Yes, you may (standard).

Yes, you might (non-standard).

Do not use might to express wishes and hopes:

May you prosper exceptionally (standard).

Might you prosper exceptionally (non-standard).

Notably, too, ‘may’ can be deployed to politely make a comment, whereas ‘might’ can be enlisted to politely offer suggestions:

You look stunning, if I may say so (a comment).

You might contact a customer care representative (a suggestion).


Shall is used alongside the first person pronouns, ‘I’ and ‘we’, to portray future actions. Do not deploy the second person pronoun (you) and third person pronouns (he, she, they, it) in this context.

I shall be a PhD next year.

We shall go to the movies tomorrow.

S/he shall go to the movies tomorrow (non-standard).

It shall be delivered of puppies soon (non-standard).

Conversely, second and third person pronouns—as well as nouns—can be used alongside shall, when expressing determination, threat, or when giving an order.

Kunle is determined that you shall pass the examinations (determination).

The students shall not enter their classrooms unless they have paid the tuition fees (order/instruction).

If he makes a noise, he shall be spanked (threat).

Of course, should is the past tense of shall. It is used to express obligation, as in:

You should be a good role model to your siblings.

Should is equally deployed when making a polite request or when requesting permission:

Should we lend him a helping hand (request)?

Should I take the car out (permission)?


‘Will’ is used to express future actions, just like ‘shall’, but the former can be deployed alongside second and third person pronouns.


S/he shall go to the movies tomorrow (non-standard).

It shall be delivered of puppies soon (non-standard).


S/he will go to the movies tomorrow (standard).

It will be delivered of puppies soon (standard).

Both ‘will’ and ‘would’ can be used to make a request, as instanced hereunder:

Will you lend me $5?

Would you lend me $5 (more polite)?

On top of that, would (not, will) is used to express preference:

I will prefer butter to mayonnaise (non-standard).

I would prefer butter to mayonnaise (standard).

Shola will rather you studied accounting (non-standard).

Shola would rather you studied accounting (standard).


This modal verb is used to express something obligatory or vital:

You must read your Bible and pray to God every day.

It can likewise be used to express the likelihood of a development or to reach a logical conclusion, as in:

You must have prepared well for the interview (a logical conclusion).

Anthony must be famished after reading for few hours (expressing likelihood).


This modal verb expresses habitual actions. ‘Used to do something’ expresses actions that regularly occurred in the past, but not anymore. ‘Be used to doing something’ expresses actions that regularly occurred in the past and still occur now. Consider this juxtaposition:

I used to live in Abuja. (I do not live there anymore.)

I am used to living in Abuja. (I have been living there, so I am familiar with the location.)


This can be used interchangeably with ‘should’, especially when stating obligation and offering advice:

You ought to (should) be a good role model to your siblings.

You ought to (should) exercise yourself regularly.

In conclusion, this treatise would serve as a reference material for anyone who hopes to deploy the modal auxiliary verbs appropriately. The readership should note that the past forms of these modal verbs do not express only past actions.

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