Modal verbs (can, may, will, shall, ought to, etc.) account for 15% of total verb usage in the English language – which means you cannot be an effective communicator if you mix up your modals. While they are more commonly used in speech (as opposed to writing), modal auxiliaries are an important aspect of language and enable the speaker or writer to express themselves with greater precision and clarity. For example:
- I can do this tomorrow (expresses ability).
- I must do this tomorrow (expresses obligation).
- I shall do this tomorrow (expresses intent).
- I might do this tomorrow (expresses possibility).
One reason modal auxiliaries can be difficult to master is that their meanings change with changes in context. Oftentimes, two or more modals can mean the same thing. For example, the modal verbs used in all the following sentences are asking for permission:
- May I do this tomorrow?
- Might I do this tomorrow?
- Could I do this tomorrow?
- Can I do this tomorrow?
This confuses many non-native speakers, who then rely on modal adjectives (possible, probable), modal nouns (probability), or modal adverbs (perhaps) to get their point across. Avoidance of modals, however, makes the speaker’s language appear stilted or unnatural to native ears.
This article introduces students, native and non-native, to modal verbs and demonstrates their correct usage with examples. It also gives a general idea of how and when to use modals and helps acquire a greater understanding of their subtleties.
What Are Modal Verbs?
Modal verbs (also called modals, modal auxiliaries, modal auxiliary verbs, helping verbs) are a special kind of irregular verbs. They precede the main verb (play, sing, make, etc.) and provide supplementary information about it.
Modals perform a variety of communicative functions; they are generally used to indicate permission, prohibition, possibility, probability, ability, obligation, advice, lack of necessity, logical conclusion, or certainty. They are used to express an attitude or opinion or to provide instruction and are always an expression of the writer’s or speaker’s view of the world.
What Are Semi-Modal Verbs?
In English grammar, a semi-modal verb (also known as a modal phrase) is a phrase based on a “pure” modal verb that shares some of the same grammatical characteristics. Some commonly used semi-modals include ought to, used to, be able to, be about to, have to, be likely to, had better, be supposed to, would rather, need and dare. To some extent, semi-modals function as modal verbs, especially in the way they form interrogative and negative sentences. For example:
- I ought to be going now.
- My brother used to be a teacher.
- I would rather sing than dance.
- Dare I ask what’s for lunch today?
- Passengers have to show their boarding pass before boarding an airplane.
- She had better not go out tonight.
Below is a list of modals and modal phrases with examples:
| MODAL VERB | EXPRESSING | EXAMPLE |
| Can, could, may, might | Permission | Can I borrow your book please? Could I say something if you don’t mind? May I use your phone please? Might I accompany you to the theatre? |
| Must not | Prohibition | You must not drive under the influence of alcohol. |
| Can, could, may, might | Possibility | Drunken driving can cause accidents. It could rain tonight. It may be sunny tomorrow. I might visit my cousins next week. |
| May, might | Probability | The store may be closed today. I might order pizza for dinner. |
| Can, could | Ability | Fred can dance like a pro. I could have done this yesterday. |
| Must, shall, should, ought to | Obligation | You must eat everything on your plate. There shall be no smoking on the premises. I should/ought to see a doctor for my frequent headaches. |
| Should, ought to, had better, would | Advice | You should/ought to review your notes thoroughly before a test. I had better go before it is too late. I would exercise every day if I were you. |
| Need not | Lack of necessity or obligation | You need not heed my advice if you don’t want to. |
| Must, should, ought to | Logical conclusion/certainty | You should/ought to be very tired. You’ve been on your feet all day. I can’t find my phone anywhere. I must have forgotten it at Jenny’s. |
| Will, would | Desire, preference, choice, consent | I will take you up on your offer. I would rather not go to school today. |
| Shall | Suggestion | Shall we go home now? |
What Are the Rules for Using Modals?
1. The modal verb that precedes the main verb must be used in its root form rather than the infinitive (where to is used.)
- Correct – I could make dinner tonight.
- Incorrect – I could to make dinner tonight.
2. The verb do can be used as a main verb as well as a modal verb. For example:
- Main verb – I shall do it tomorrow.
- Modal verb – You do read books, don’t you?
3. However, do can be used as a modal verb only if no other modal verb is being used in the sentence. For example:
- Correct – Thank you, I do know where the library is.
- Incorrect – Thank you, I might do know where the library is.
What Are Past Modals?
Past modals – could have, should have, would have – are used in combination with a past participle verb. They are hypothetical expressions of present feelings about past actions or decisions about things that didn’t really happen in the past.
1. She could have married anyone she wanted.
Meaning – Something was possible in the past, but it didn’t happen.
2. I would have gone to the party, but I had to finish that term paper.
Meaning – I wanted to do something in the past but couldn’t.
3. He should have taken better care of himself.
Meaning – Something didn’t happen but we wish it had.
Unlike the simple past tense (that merely conveys what actually happened), past modals tell you what could have, should have, or would have happened in the past (except it didn’t). For example:
Simple past tense
- I did not cook dinner last night.
Past modal
- I could have cooked dinner last night.
- I would have cooked dinner last night, but I was too tired.
- I should have cooked dinner last night.
What Are the Functions of Modals?
Most modals and semi-modals convey two kinds of meaning.
1. The writer/speaker predicts or speculates about something in the past, present, or future. This is what is implied when we talk about degrees of possibility, certainty, doubt, or likelihood of a fact. For example:
- John won’t be home for hours. He left for work five minutes ago.
- I may go to the party if I find a babysitter for the children.
2. The writer or speaker seeks to direct, control, or prohibit an action or give/refuse permission. They refer to necessity and obligation and describe how they want the world to be.
- You can play outside when you finish your homework.
- I ought to exercise more.
- You must focus on the job at hand.
- Tell Marcia she needn’t bother doing the laundry.
Take this test to see how well you know your modals:
1. You ______ start the test now.
- might
- may
2. Jen ______ help her sister with her homework last night.
- couldn’t
- can’t
3. All assignments ______ be turned in by Monday.
- would
- must
4. The doctor ______ see you now.
- can
- could
5. There ______ no trespassing on this property.
- should be
- shall be
6. Jim ______ plagiarize an essay, would he?
- wouldn’t
- won’t
7. You ______ play the piano if you don’t want to.
- mayn’t
- needn’t
8. We ______ leave now or we will miss the bus.
- should
- could
9. ______ we meet next week?
- Should
- Shall
10. I ______ like a cup of tea, please.
- will
- would
11. Michael ______ swim very well.
- can
- must
12. ______ you like another drink?
- Could
- Would
13. If you go to the Bahamas, you ______ take lots of pictures.
- would
- must
14. You ______ talk loudly in the library.
- can’t
- mustn’t
15. Excuse me, ______ I borrow your phone?
- may
- should
16. It’s quite late. The kids ______ be fast asleep.
- shall
- will
17. I wish I ______ play tennis like Nadal.
- might
- could
18. It ______ rain this weekend.
- should
- must
19. Excuse me, ______ I have the menu please?
- would
- could