Modal Verbs: Overview

Form

Affirmative 

He can swim.

subject + modal verb + base verb

Negative 

He cannot / can’t swim.

subject + modal verb + negator + base verb

Question 

Can you swim?

modal verb + subject + base verb

Note: “Do” is not used for negatives, questions, or question tags.

Meaning and Use

• Modal verbs (a type of auxiliary verb) add a functional meaning to the main verb.
• They don’t have aspect (progressive, perfect)
• They don’t change for person (third person singular does not include -s).

Modal verbs are divided into two groups:

• Modal verbs (can, could, will, etc.)
• Semi-modal verbs (have to, need, used to, be able to, etc.) that function as modal verbs but don’t follow the grammatical rules.

List of modal verbs

Although it’s recommended to learn them based on different usage groups, here is a non-exhaustive list of modal verbs:

• can / can’t / cannot
• could / couldn’t / could not
• will / won’t / will not
• shall / shan’t (not common) / shall not
• should / shouldn’t / should not
• would / wouldn’t / would not
• may / may not
• must / mustn’t (not common) / must not

Semi-modals (which don’t all follow the grammatical rules for other modals):

• have [got] to / don’t have to
• need / needn’t (not common) / need not
• dare / daren’t (not common) / dare not
• used to / didn’t use to
• ought to / oughtn’t to (not common) / ought not to
• had better / had better not
• must have / can’t have
• must be / can’t be
• be able to

Categories

Modal verbs can be put into different categories:

• Requests, Orders, Offers, and Permission (can, could, will, would, may, might)
• Ability (can, can’t, could, couldn’t)
• Obligation and Compulsion (must, have to, should, ought)
• Possibility and Certainty (may, might, could, must, must have, can’t, can’t have)

Notice that some modal verbs (such as can and could) are in multiple categories such as can and could.

Tips & Tricks

Some modal verbs have multiple usages (i.e. could, can).

It’s best to learn modal verbs based on different usage categories.

---

References

• Scrivener, Jim. Teaching English Grammar: What to Teach and How to Teach It. Oxford, Macmillan Education, 2010.