Modals or modal auxiliary verbs are the verbs that combine with another verb to indicate mood or tense. Modals are always accompanied by other verbs. They are never conjugated and are followed by the present form of the verb. Since they do not change their forms according to the number or person of the subject, they have no –s or –es added in the third person singular present tense.

Modals are used for expressing

a) Ability

b) Possibility

c) Probability

d) Permission

e) Advisability

f) Necessity

g) Requesting assistance

Shall and Will

To express simple future, ‘Shall’ is used in the first person and ‘Will’ in the second and third persons. Shall’ with the second or third person expresses a command, a promise, a threat or determination. Will’ is used in the first person to express willingness, a promise, a threat or determination. ‘Shall’ indicates simple futurity in the second person and it also expresses command or desire of the person spoken to with the third person.


Should follows the same rules as ‘Shall’ in assertive and interrogative sentences. It expresses a future event. ‘Should’ can also be used to express supposition or condition. Another use of ‘should’ is to express a purpose.


Would generally follows the same rules as ‘Will’ in assertive and interrogative sentences. Would is used

a) To express a wish

b) To express a condition

c) To express determination

d) To express habit


Can is used to express

a) Power or strength

b) Permission

c) Possibility


Could is the past tense of can. It is an auxiliary verb and is used

a) As a transitive verb

b) To denote permission

c) To denote condition


May is used

a) To denote permission

b) Possibility

c) A wish or a prayer

d) A purpose

e) Question


Might is the past tense of ‘may’. It is used to denote

a) Permission

b) Suggestion

c) Possibility

d) Wish

e) Purpose

f) Reproach


Must expresses the following

1. Compulsion

2. Duty/obligation

3. Determination

4. Certainty

Ought to

The verb ‘Ought’ is Transitive and the Infinitive following is its object. It is used only in the sense of duty or moral obligation; as,

We ought to respect our parents. (Present)

You ought not to have said that. (Past Participle)

Used to

The Past tense ‘used to’ expresses what was repeatedly seen or done during a period of time in the past; as,

I used to learn music as a kid.

‘Used to’ means accustomed to; as,

I am not used to taking oats and milk in the morning.

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