Modal Verb: Definition, Examples & Rules | English Grammar
Last Updated: 01 Jul, 2025
Welcome! In this lesson, you'll learn everything you need to know about Modal Verbs in English grammar. We'll cover what they are, why they matter, how to use them, and how to avoid common mistakes. You'll also find real-life examples, a quick quiz, and pro tips to help you master this essential grammar topic.
What is a Modal Verb?
Modal Verb Definition: A Modal Verb is a type of auxiliary verb that expresses modality - such as ability, possibility, permission, obligation, or necessity. Modal verbs help to modify the meaning of the main verb in a sentence.
Why are Modal Verbs Important? They are essential for expressing attitudes, opinions, and degrees of certainty. Modal verbs help us communicate what we think, what we can do, what we should do, and what might happen.
Function in Grammar
Modal verbs are auxiliary verbs that express modality. They are always followed by the base form of the main verb and help to convey the speaker's attitude or the likelihood of an action. For example:
- I can swim. (Ability)
- You should study. (Advice)
Modal Verb vs Regular Verb: Modal verbs express attitude and possibility, while regular verbs express actions and states.
Types of Modal Verbs
| Modal Verb | Function | Example |
|---|---|---|
| can | Ability, possibility, permission | I can swim. |
| could | Past ability, polite request | I could swim when I was young. |
| may | Permission, possibility | You may enter. |
| might | Possibility, uncertainty | It might rain. |
| must | Obligation, strong necessity | You must study. |
| shall | Future intention, offer | I shall help you. |
| should | Advice, recommendation | You should study. |
| will | Future, willingness | I will help you. |
| would | Polite request, hypothetical | Would you help me? |
Modal verbs express different types of modality and attitude.
📌 Modal Verb Challenge!
Can you identify which words are modal verbs in these sentences?
- I can swim.
- You should study.
- He might come.
Show Answers
- can (expresses ability)
- should (expresses advice)
- might (expresses possibility)
Examples of Modal Verbs in Sentences
- I can speak English fluently.
- You should visit the doctor.
- He might arrive late.
- She must finish her homework.
- We will help you tomorrow.
- They could solve the problem.
- You may use my pen.
- I would like some coffee.
- She shall return soon.
- He must be at work by 9 AM.
- We can meet for lunch.
- You should try this restaurant.
- It might rain today.
- They will arrive on time.
- I could help you with that.
Notice how each modal verb expresses a different attitude or degree of certainty.
Modal Verbs vs Regular Verbs
Key Differences
| Aspect | Modal Verb | Regular Verb |
|---|---|---|
| Function | Express modality | Express action/state |
| Form | No -s for 3rd person | Add -s for 3rd person |
| Following Verb | Base form | Various forms |
| Example | He can swim. | He swims. |
Modal verbs express attitude, while regular verbs express actions.
Special Rules and Notes
- Base Form: Modal verbs are always followed by the base form of the main verb (without 'to').
- No -s Ending: Modal verbs don't add -s for third person singular (He can swim, not He cans swim).
- No Infinitive: Modal verbs don't have infinitive forms (no "to can" or "to must").
- No -ing Form: Modal verbs don't have -ing forms (no "canning" or "musting").
- Past Forms: Some modal verbs have past forms (can/could, will/would, may/might).
- Negation: Modal verbs form negatives by adding 'not' (cannot, should not, must not).
- Questions: Modal verbs can be inverted to form questions (Can you swim?).
- Perfect Infinitive: Modal verbs can be followed by perfect infinitives (He must have left).
Quick Quiz: Spot the Modal Verb!
Which words are modal verbs in these sentences?
- I can speak English fluently.
- You should visit the doctor.
- He might arrive late.
- She must finish her homework.
- We will help you tomorrow.
- They could solve the problem.
- You may use my pen.
- I would like some coffee.
Answers: can, should, might, must, will, could, may, would
🔧 Sentence Correction Challenge!
Can you spot and fix the mistakes in these sentences?
- He cans swim. (Incorrect - modal verb with -s)
- I can to swim. (Incorrect - modal verb with 'to')
- She musts study. (Incorrect - modal verb with -s)
Show Corrected Sentences
- He can swim. (Remove -s from modal verb)
- I can swim. (Remove 'to' after modal verb)
- She must study. (Remove -s from modal verb)
Frequently Asked Questions
What is a modal verb?
A modal verb is a type of auxiliary verb that expresses possibility, necessity, ability, permission, or obligation. Modal verbs help convey the speaker's attitude toward the action. Examples include can, could, may, might, must, shall, should, will, and would.
What are examples of modal verbs?
Examples include can, could, may, might, must, shall, should, will, would, and ought to. These verbs express different meanings like ability, possibility, necessity, permission, and obligation.
How do modal verbs differ from regular verbs?
Modal verbs don't change form for person or number (I can, he can), don't have infinitive or participle forms, and are always followed by the base form of the main verb. They express attitude rather than action.
What are the main functions of modal verbs?
Modal verbs express ability (can), possibility (may/might), necessity (must), permission (may/can), obligation (should/must), and future intention (will). They help convey the speaker's perspective on the action.
Can modal verbs be used in all tenses?
Modal verbs have limited tense forms. They don't have past participles or present participles. Some have past forms (can/could, will/would), while others use different constructions for past meaning.
What is the difference between "can" and "could"?
"Can" expresses present ability or permission, while "could" expresses past ability, polite requests, or hypothetical situations. "Could" is also more polite than "can" when making requests.
How do you form questions and negatives with modal verbs?
For questions, invert the modal verb with the subject: "Can you swim?" For negatives, add "not" after the modal verb: "cannot" or "can't", "should not" or "shouldn't".
Why are modal verbs important?
Modal verbs are essential for expressing attitudes, possibilities, and degrees of certainty in English. They help us communicate more precisely about ability, permission, necessity, and probability.
Conclusion
Understanding modal verbs is crucial for expressing attitudes, opinions, and degrees of certainty in English. These auxiliary verbs help us communicate what we think, what we can do, what we should do, and what might happen. Always remember that modal verbs are followed by the base form of the main verb and don't change form for third person singular. Pay attention to the different types of modality they express - from ability and possibility to obligation and advice. Practice identifying and using them in your writing and speech. The more you practice, the more naturally you'll be able to express your thoughts and attitudes using modal verbs!