Modal verbs, also known as ‘auxiliary verbs’ or ‘modals’, belong to a category of verbs that are not used on their own, but are used to ‘help’ the main verb (or action word) in a sentence. The definition of ‘auxiliary’ is to provide help and support, which is why they are given this name. Modal/auxiliary verbs, are a specific category of verbs that are used to express modality. Modality means the ‘mode’, or the manner of something, or the way something is. In the grammatical sense, modality refers to the speaker or writer’s attitude, which could be one of the following: certainty, permission, ability, possibility or necessity regarding the action or state described by the main verb in a sentence. Modal verbs modify or add nuances to the meaning of the main verb.
Many languages around the world have modal verbs similar to those found in English. While the specific modal verbs and their nuances may vary from one language to another, examples of languages with modal verbs include Spanish (‘poder’ for ‘can’ or ‘deber’ for ‘should’), German (‘können’ for ‘can’ or ‘müssen’ for ‘must’), and French (‘pouvoir’ for ‘can’ or ‘devoir’ for ‘must’).
Examples of the most common English modals
These are the most common auxiliary verbs,
- May
- Might
- Can
- Be able to
- Could
- Would
- Used to
- Will
- Have to
- Must
- Need to
- Should
- Ought to
Before continuing on to the article, see if you know any of the above modals and think about how you might use them in a sentence.
Modal verbs and what they express
- May: politeness, permission, possibility or uncertainty
- Might: possibility or uncertainty
- Can: ability, permission or possibility
- Be able to: ability, permission or possibility
- Could: permission, possibility or past ability – it can be used as the past tense of ‘can’
- Would: past habits, polite requests or hypothetical situations
- Used to: past habits
- Will: future action or intention
- Shall: primarily formal or legal contexts to express future action or intention
- Have to/ Must: necessity, obligation or strong probability
- Need to: necessity or obligation
- Should: advice, recommendation or obligation
- Ought to: moral obligation or duties
The basics
Modal verbs are verbs or short verb phrases that assist main verbs in a sentence.
You will notice in the examples above that some of the modal verbs have the preposition ‘to’ next to them and some don’t. When a modal verb does not have ‘to’ beside it in its base form, there is no need to add ‘to’ to it in a sentence. Typically, the main verb takes the infinitive form without ‘to’:
- I used to go skiing
- I have to go shopping
The above modal verbs have ‘to’ as part of their base form, but most modals don’t:
- I should go shopping
- I might go skiing
The modal verb usually comes before the main verb, but one can place an adverb between:
- I may quickly go to the shop.
- I may go to the shop.
- I will probably be late.
- I will be late.
Or if the sentence is formed as a question, in which case the subject must come in between the modal verb and the main verb:
- Will you drive safely, please?
- What time should we go out?
For further details see this article on forming questions in English.
It is also important to note that modal verbs do not add -s to the third person singular form of the main verb:
- Bob plays football well
- Bob can play football well
- Sarah bakes excellent cakes
- Sarah will bake a cake for tonight
You may also have noticed from the above examples that the modal verb itself also does not take any inflection such as -s, -ed, or -ing.
However, the above rules are true only for those modal verbs that appear alone: may, might, can, could, would, will, shall, should. Of those modal verbs that include ‘to’: ought to, need to, be able to, used to there are two exceptions to these rules: need to and be able to:
- Sarah could bake excellent cakes
- Bob can play football well
- Gina ought to try harder
- Donna used to eat a lot of chocolate
- Sam needs to study more
- Susie is able to spell accurately
Notice in the last two examples, ‘need to’ and ‘be able to’ break the standard ‘no 3rd person singular inflection rule’ for modal verbs. Note also that the 3rd person is expressed through the modal verb and not the main verb in these two exceptive cases.
Modal verbs with examples:
- May: It may be evening in London. May I sit here?
- Might: I might go out tonight. He might arrive late. Might I request a favour?
- Can: She can’t be serious. Can you take my coat? We can ask her tomorrow. You can do it!
- Be able to: Are you able to do it? She won’t be able to come tonight.
- Could: Could you talk a little louder?
- Could (for the past): I couldn’t swim until I was ten.
- Would: Would you mind passing me the butter? I would go if I could.
- Would (for the past): When I was young, I would climb trees often.
- Used to: I used to work at that shop. She used to be so pretty.
- Will: That will never happen. He will make the cake for the party. She will do well.
- Shall: Shall we meet again? Shall we have pizza?
- Have to: I have to go to the doctor later. My daughter has to do her homework.
- Must: I must give you my phone number. You mustn’t speak unless you are spoken to.
- Need to: I need to buy some new shirts.
- Should: I should really go.
- Ought to: We ought to leave now. You ought to listen more carefully.
Curious additional notes about the word ‘may’
The modal verb ‘may’ has evolved somewhat differently to other modal verbs in the English language and, in the present day, can only be used to form a question with the first or third person singular or plural.
- Could I/we have more tea?
- Should I/we have more chocolate?
- May I/we have more milk?
Look what happens in the second person:
- Could you walk faster? (acceptable)
- Should you give me a hand? (acceptable)
- Would you walk with me? (acceptable)
- May you walk with me? (unacceptable)
In this sense, the word ‘may’ presents a grammatical anomaly!
Using modal verbs in the past tense
In a sentence in the present tense not containing a modal verb, the main verb changes to the past participle:
- I walk becomes I walked
- I laugh becomes I laughed
The past tense of modal verbs is formed by combining the modal with the word ‘have’ and the past participle of the main verb.
So, expressed with a modal verb:
- I might walk becomes I might have walked
- I would laugh becomes I would have laughed
In this way the modal verbs are still expressing missed obligations or uncertainties, but now they relate to the past instead of the present:
- She should have driven him home.
- He may have left early.
- He will have gone home now.
For further clarification on the past participle please see the relevant post.
Exercises to practise
Fill in the relevant modal verb in the example sentences below.
Conclusion
English modal verbs are often used in conjunction with the base form of the main verb in a sentence. They can also be combined with other modal/auxiliary verbs to create additional meanings or tenses. This is not an exhaustive list of modals and you may come across others.
If you have any comments or questions, please do post them below.
BIBLIOGRAPHY
Crystal, David. The Cambridge Encyclopedia of the English Language, 3rd edn (Cambridge University Press, 2019)
Dreyer, Benjamin. Dreyer’s English: An Utterly Correct Guide to Clarity and Style (Penguin Random House, 2020)
Gwynne, N. M. Gwynne’s Grammar: The Ultimate Introduction to Grammar and the Writing of Good English (Ebury Press/Random House, 2013)
Hewings, Martin, and others. Cambridge English Grammar and Vocabulary for Advanced (Cambridge University Press, 2015)
Huddleston, Rodney, and others. The Cambridge Grammar of the English Language (Cambridge University Press, 2002)
Parrott, Martin. Grammar for English Language Teachers, 2nd edn (Cambridge University Press, 2011)
Quirk, Randolph, and others. A Comprehensive Grammar of the English Language, reprint edn (Pearson, 2011)
Seely, John. Oxford A – Z of Grammar & Punctuation (Oxford University Press, 2020)
Hey, this is quite informative. It offers a clear explanation of these essential components of the English language. Your examples help illustrate how modal verbs are used in various contexts.I
‘m curious if you can provide any practical exercises or additional resources to help learners practice and improve their understanding of modal verbs.
Hi Jake. Thanks for your comments. I am glad you found this post useful. Did you see the section at the bottom with exercises to practise? Also, new exercises are regularly added to this website and you can find them under ‘Quizzes’ in the main menu.
Hi Michelle,
Your article is a commendable exploration into modal verbs and a vital resource for learners at various stages of English proficiency. You provide clear definitions and lots of examples.
Your article not only aids in comprehension but your careful curation of examples, from the basic functions of “may” and “must” to the subtle distinctions in past tense usage, equips readers with the more advanced knowledge and has improved my confidence.
Comprehensive coverage, practical insights, and engaging presentation.
Thank you Gary! I appreciate your feedback.