Modal Verbs

5 min

Mastering Helping Verbs for Mood, Ability, and Probability

The Golden Rule of Modals

Modal verbs express the speaker's mood or attitude like ability, permission, or necessity. A modal is always followed by the bare infinitive (V1) without 'to'. They never change form based on the subject.

Why Exams Target Modals

Error spotting often tests the redundant use of 'can' with 'able to'.
The fixed pairing of 'lest' with 'should' is a favorite SSC question.
Differentiating between 'must not' (prohibition) and 'need not' (lack of necessity).

Quick Memory Hooks

M + V1: Always use Bare Infinitive (V1) after a Modal.
Lest-Should: 'Lest' always takes 'should', never 'would' or 'may'.
Past Habit: Use 'used to' or 'would' for repeated past actions.

Modal Usage Guide

Modal	Usage	Example
Can / Could	Ability	I can lift this.
May / Might	Possibility	It may rain.
Must / Have to	Obligation	You must go.
Ought to	Moral Duty	We ought to pray.

Modals in Action

Can

(Mental Ability)

Mental Ability

He can solve it.

Should

(Direct Advice)

Direct Advice

You should study.

Lest

(Fear/Warning)

Fear/Warning

Run, lest you fall.

Must Not

(Prohibition)

Prohibition

You must not smoke.

Common Exam Traps

He can be able to do it.He can do it.

'Can' and 'able to' both show ability; using both is redundant.

Work hard lest you may fail.Work hard lest you should fail.

'Lest' must always be followed by 'should'.

She will to go tomorrow.She will go tomorrow.

Modals take V1 directly, never 'to + V1'.

Practice Questions

Q1.Walk carefully lest you _______ stumble.

Q2.You _______ not enter the restricted area.

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