Can, could, may, might, must, should, will, would and more, every modal verb explained with its full range of meanings, from ability and permission to obligation and deduction.
๐ Reading time: ~28 minutesโ Reviewed by a CELTA-qualified teacher๐ฏ Covers A2 to C1
Modal verbs are a small but powerful group of auxiliary verbs, can, could, may, might, must, shall, should, will, would, that change the meaning of the main verb to express ability, permission, possibility, obligation, advice, deduction and more. They are some of the most frequently used words in English, and also some of the most nuanced: the same modal verb often carries several distinct meanings depending on context.
Take "must," for example. "You must wear a seatbelt" expresses obligation. "She must be tired after that journey" expresses a logical deduction. Same word, completely different function. This is precisely what makes modal verbs challenging, and precisely why this guide organises them by meaning (ability, permission, obligation, possibility, deduction) rather than simply listing each modal in isolation.
Modal verbs are also grammatically unique in English: they never take -s in the third person, they are always followed by the base form of the verb (with no "to"), and they have no infinitive or -ing form. This guide explains both the grammar and the meaning, fully.
Why Do Modal Verbs Matter?
They express nuance and certainty, the difference between "it might rain" and "it must rain" and "it will rain" reflects genuinely different levels of confidence.
They are essential for politeness in requests, offers and suggestions: "Could you help me?" is far more natural than "Can you help me?" in many contexts.
Every major exam tests modal verbs extensively, particularly the distinction between similar modals (must vs have to, may vs might, should vs ought to).
Who Should Learn This Page?
This guide covers A2 (elementary) through C1 (advanced). Basic modals (can, must, should) are typically introduced at A2. The full range of meanings, deduction, past modals, advanced politeness structures, extends through B1, B2 and into C1.
๐ก
How to use this guide
This guide is organised by meaning, not by individual modal verb, because the same modal often has several different uses. Find the meaning you need (ability, permission, obligation, possibility, deduction) and you'll see all the modals that can express it, with the subtle differences between them.
2. Quick Summary
โก Modal Verbs at a Glance
DefinitionAuxiliary verbs that express ability, permission, obligation, possibility or deduction.
StructureSubject + modal + base verb (no "to," no -s, no tense change)
Full Listcan, could, may, might, must, shall, should, will, would (+ semi-modals: have to, need to, ought to)
Example"You should see a doctor." "She might be late."
Common MistakeAdding "to" after a modal: "I can to swim" instead of "I can swim"
Memory TipModal + base verb, always. Never -s, never "to," never a different tense form.
3. The Grammar Rule, How Modals Behave Differently
Modal verbs follow completely different rules from ordinary verbs. They never change form, never need "do/does" for questions or negatives, and are always followed by the base form of the main verb.
Rule
Example
No -s in third person
She can swim. (NOT "She cans swim")
Followed by base form, never "to"
I must go. (NOT "I must to go")
No "do/does" for questions
Can you help me? (NOT "Do you can help me?")
No "do/does" for negatives
I cannot swim. (NOT "I don't can swim")
No infinitive or -ing form
There is no "to can" or "canning" as a modal
The Full List of Modal Verbs
Modal
Negative Form
Contraction
can
cannot / can not
can't
could
could not
couldn't
may
may not
(no common contraction)
might
might not
mightn't (rare)
must
must not
mustn't
shall
shall not
shan't (rare, very formal British)
should
should not
shouldn't
will
will not
won't
would
would not
wouldn't
Semi-Modals: Have To, Need To, Ought To
These behave slightly differently, "have to" and "need to" follow normal verb rules (taking -s, using do/does), while "ought to" behaves like a true modal except it is followed by "to."
Semi-Modal
Behaviour
Example
have to
Conjugates normally; uses do/does
She has to leave. Does she have to leave?
need to
Conjugates normally; uses do/does
He needs to study. Does he need to study?
ought to
No -s, no do/does, but keeps "to"
You ought to apologise. (NOT "You oughts to" or "Do you ought to")
4. Sentence Structure
Form
Structure
Example
Positive
Subject + modal + base verb
You should rest.
Negative
Subject + modal + not + base verb
You should not rest yet.
Question
Modal + subject + base verb?
Should you rest?
Short Answer
Yes/No, subject + modal (+not).
Yes, you should. / No, you shouldn't.
5. Can, Could, Be Able To, Ability
Modal
Use
Example
can
Present ability
I can speak three languages.
could
Past general ability
I could swim when I was five.
was/were able to
Past ability on a specific occasion (success)
I was able to finish the marathon despite the rain.
will be able to
Future ability
After this course, you will be able to hold a conversation in English.
โ ๏ธ
"Could" vs "was able to" for a single past achievement
For a one-time specific past achievement (especially involving difficulty or effort), "was/were able to" is more accurate than "could." "I could pass the exam" sounds odd; "I was able to pass the exam" is correct. "Could" works well for general past ability ("I could read by the age of four") but not for a single, specific successful event.
6. Can, Could, May, Permission
Modal
Formality
Example
can
Informal, everyday
Can I leave early today?
could
More polite
Could I leave early today?
may
Formal, polite
May I leave early today?
7. Must, Have To, Should, Ought To, Obligation & Advice
Modal
Strength / Source
Example
must
Strong obligation, often from the speaker's own authority/feeling
You must finish this by Friday. (I, the speaker, insist)
have to
Strong obligation, often from an external rule/authority
You have to wear a uniform at this school. (it's a school rule, not my opinion)
should
Advice or recommendation, not obligatory
You should see a doctor about that cough.
ought to
Similar to should, slightly more formal
You ought to apologise to her.
๐ก
Must vs Have To, the source of the obligation
"Must" often implies the speaker's personal authority or strong feeling ("You must come to my party!"). "Have to" often implies an external rule or requirement ("I have to renew my passport before I travel", it's a legal requirement, not my personal opinion). In practice, native speakers often use them interchangeably in everyday speech, but the distinction is tested in exams.
8. Mustn't vs Don't Have To, A Critical Distinction
This is one of the most frequently tested, and most frequently confused, pairs in all of English grammar. They look similar but mean almost opposite things.
Form
Meaning
Example
mustn't
It is prohibited / forbidden, you are not allowed to
You mustn't smoke in here. (= it is forbidden)
don't have to
It is not necessary, but you are allowed to if you want
You don't have to come to the meeting if you're busy. (= it's optional)
โ ๏ธ
This distinction is genuinely critical
"You mustn't park here" means parking is forbidden. "You don't have to park here" means parking is optional, you could park elsewhere if you prefer, but there's no rule against it here. Confusing these two completely reverses the meaning of the sentence, and is one of the single most common, and most consequential, modal verb errors.
9. May, Might, Could, Possibility
Modal
Degree of Certainty
Example
may
~50%, slightly more formal
It may rain later.
might
~50%, slightly less certain than "may," very common
A distinct, advanced use: modals expressing how confident the speaker is about something being true, based on evidence or logic, not about obligation or ability at all.
Modal
Certainty Level
Example
must
Very confident it's true (positive deduction)
She must be tired, she's been working all day.
can't
Very confident it's NOT true (negative deduction)
That can't be right, the shop closed an hour ago.
might/may/could
Uncertain, possible
He might be stuck in traffic, that would explain why he's late.
๐
Deduction is a high-value exam topic
This use of modals, drawing logical conclusions from evidence, is specifically tested at B2 and above. Note that "mustn't" is never used for negative deduction; "can't" is used instead: "That can't be true" (not "That mustn't be true").
11. Modal Verbs in the Past
Most modals form their past equivalent using "modal + have + past participle", a structure that causes significant difficulty because it requires combining modal meaning with past time reference.
Past Modal
Meaning
Example
must have + past participle
Confident past deduction
She must have left already, her car isn't here.
can't have + past participle
Confident negative past deduction
He can't have finished already, it's only been five minutes.
might/may have + past participle
Uncertain past possibility
They might have missed the train.
should have + past participle
Past advice not followed / regret
You should have called me, I was worried.
shouldn't have + past participle
Criticism of a past action that did happen
You shouldn't have spent so much money.
could have + past participle
Past possibility that didn't happen
I could have helped you if you'd asked.
would have + past participle
Hypothetical past result (third conditional)
If I had known, I would have told you.
โ ๏ธ
"Should have" expresses regret, not present obligation
"You should have studied harder" means you didn't study harder, and now there is a negative consequence (probably failing an exam). This is fundamentally different from "You should study harder," which is present-tense advice for the future.
12. Choosing the Right Modal, Quick Reference
What You Want to Express
Best Modal(s)
Present ability
can
Past general ability
could
Past specific achievement
was/were able to
Informal permission
can
Polite/formal permission
could, may
Strong obligation (personal)
must
Strong obligation (external rule)
have to
Advice
should, ought to
Prohibition
mustn't
No obligation
don't have to, don't need to
50% possibility (future)
may, might, could
Confident positive deduction (present)
must
Confident negative deduction (present)
can't
Past regret/criticism
should have / shouldn't have
13. British vs American English
Situation
British English
American English
"Shall" for suggestions
Common: "Shall we go?"
Rare; "Should we go?" or "Let's go" preferred
"Have got to" for obligation
Very common informally: "I've got to go"
Used but less frequent; "I have to go" or "I gotta go" more typical
"Needn't" as a modal
Used in formal/traditional British English: "You needn't worry"
Rare; "You don't need to worry" preferred
"May" for permission
Considered correct and somewhat formal
Similar usage, though "can" is more dominant informally in both varieties
14. Formal vs Informal English
Context
Example
Formal request
Might I ask you a question? / Would you be so kind as to...
Informal request
Can I ask you something? / Could you...?
Formal obligation
Applicants must submit all documentation by the stated deadline.
Informal obligation
You've got to send everything in by Friday.
Formal suggestion
You may wish to consider an alternative approach.
Informal suggestion
You could try a different way, maybe?
15. Spoken English & Contractions
Full Form
Spoken Contraction/Reduction
cannot
can't
will not
won't
should have
should've (often sounds like "should of", never written that way)
have to
"hafta" (informal pronunciation only, never written)
have got to
"gotta" (very informal pronunciation, never in formal writing)
want to
"wanna" (informal pronunciation only)
โ ๏ธ
"Should of," "could of," "must of" are never correct
These come from the sound of "should've," "could've," "must've" in rapid speech, but the correct written form is always "should have," "could have," "must have."
16. Pronunciation
"Can" is usually unstressed and reduced in positive sentences: /kษn/, almost like "kn." In negatives, "can't" is fully stressed: /kษหnt/ (British) or /kรฆnt/ (American).
"Have" in past modals is often reduced to a quick /ษv/ sound: "should've," "could've," "must've", practise these as smooth single units.
Contrastive stress changes meaning: "You COULD do it" (emphasising possibility, encouraging) vs "You could DO it" (emphasising the action itself).
17. 30 Common Mistakes
โ I can to swim.
โ I can swim.
Never use "to" after a modal verb.
โ She cans speak French.
โ She can speak French.
Modal verbs never take -s, even for third person singular.
โ Do you can help me?
โ Can you help me?
Modal questions invert the modal and subject, no "do/does" needed.
โ I don't can swim.
โ I can't swim.
Modal negatives use "not" directly after the modal, not "don't."
โ You mustn't worry about the cost, it's optional.
โ You don't have to worry about the cost, it's optional.
"Mustn't" means forbidden, not optional. Use "don't have to" for "not necessary."
โ I should studied harder for the exam yesterday.
โ I should have studied harder for the exam yesterday.
Past regret requires "should have," not "should" alone with a past verb.
โ He must to be tired.
โ He must be tired.
No "to" after "must," even in the deduction meaning.
โ She could to help you.
โ She could help you.
No "to" after "could."
โ I could pass the exam yesterday.
โ I was able to pass the exam yesterday.
For a single specific past achievement, use "was/were able to," not "could."
โ You shouldn't have went there.
โ You shouldn't have gone there.
After "have" in a past modal, use the past participle "gone," not the past simple "went."
โ I must of left my keys at home.
โ I must have left my keys at home.
"Must of" is never correct, always write "must have."
โ He oughts to apologise.
โ He ought to apologise.
"Ought to" never takes -s, even for third person.
โ Do I ought to call her?
โ Ought I to call her? (rare, formal) / Should I call her?
"Ought to" doesn't use "do" for questions, though "should" is much more commonly used in questions in practice.
โ She has to studies every day.
โ She has to study every day.
After "has to," the verb stays in base form, "studies" is incorrect here.
โ I am not able to swim. (when meaning permission)
โ I'm not allowed to swim here. / I can't swim here.
"Be able to" expresses ability, not permission, use "can/can't" or "allowed to" for permission.
โ That mustn't be true, it doesn't add up.
โ That can't be true, it doesn't add up.
For negative deduction, use "can't," never "mustn't."
โ I would have liked to went.
โ I would have liked to go.
After "to," use the base form "go," not the past form "went."
โ She can swims very well.
โ She can swim very well.
No -s on the main verb after a modal.
โ I needn't to worry.
โ I needn't worry. / I don't need to worry.
When used as a true modal, "needn't" takes no "to", but "don't need to" (the more common alternative) does require "to."
โ You should to see a doctor.
โ You should see a doctor.
No "to" after "should."
โ He musts finish by Friday.
โ He must finish by Friday.
Never add -s to "must."
โ Can you to pass the salt?
โ Can you pass the salt?
No "to" after "can."
โ I might to come later.
โ I might come later.
No "to" after "might."
โ She will can help you tomorrow.
โ She will be able to help you tomorrow.
Two modals cannot be combined directly ("will can"); use "will be able to" instead.
โ You must not to be late.
โ You must not be late.
No "to" needed, "not" goes directly after the modal, then the base verb.
โ He should has called by now.
โ He should have called by now.
The auxiliary after a past modal is always "have," not "has", modals don't conjugate.
โ I would liked to help.
โ I would have liked to help. / I would like to help.
Either keep it present ("would like") or make it a clear past modal ("would have liked"), "would liked" alone is incomplete.
โ They can't have arrived already, that's impossible, it's too early.
โ They can't have arrived already.
This example is actually correct grammar, included to show that "can't have" + past participle is the right structure for confident negative past deduction, not an error to fix.
โ You don't must come if you're busy.
โ You don't have to come if you're busy.
"Must" cannot be negated with "don't", use "don't have to" to express lack of obligation.
โ I could to finish it by tomorrow if needed.
โ I could finish it by tomorrow if needed.
No "to" after "could," even in a conditional context.
18. Advanced Usage (B2โC1)
"Shall" for Formal Suggestions and Offers
"Shall" is largely restricted in modern English to suggestions and offers, particularly in British English: "Shall we begin?" "Shall I open a window?" It is rarely used for simple future prediction in contemporary English (that's "will"), though it persists in formal legal and ceremonial language ("The tenant shall pay rent monthly").
"Would" for Past Habits
"Would" can express repeated past actions, similar to "used to" but only for actions (not states): "Every summer, we would visit my grandparents." See our Past Simple guide for the full comparison with "used to."
Modals of Criticism: "Could Have" vs "Should Have"
Both look back at a missed past opportunity, but with different tones. "You could have told me" is relatively neutral, simply noting a missed opportunity. "You should have told me" carries a stronger sense of criticism or expectation that wasn't met.
Double Modals and Hedging in Advanced Speech
Advanced speakers often combine modal-like expressions for careful hedging: "I might possibly be able to help" or "It could perhaps be worth considering", layering caution for diplomatic, professional contexts.
19. Native Speaker Tips
"Could you possibly...?" is one of the most natural polite request structures in British English, softer than "Can you" and very common in professional contexts.
"I was wondering if you could..." is an extremely common indirect request, especially in emails: "I was wondering if you could send me the file."
"You might want to..." is a very British, softened way to give advice or a gentle instruction, more diplomatic than "You should": "You might want to double-check that figure."
"I can't be bothered" is a common informal expression meaning "I don't want to make the effort", note this uses "can't" idiomatically, not for ability.
20. 50 Useful Collocations
can't help itcan't standcan't waitcan't affordcan't believecould do withcould usemust admitmust saymust confessshould know bettershouldn't have botheredwould ratherwould preferwould love towould mindwould appreciatewill definitelywon't budgemay as wellmight as wellcould be worsecould go either waymust have beencan't have beenshould have knownought to knowhave got todon't have to worryneed not applycan managecan copecan handlecan deal withcould really usemight considermay wish toshould considermust ensurehave to admitwill have towould have tocould have swornmust be jokingcan't possiblymight not be able toshould be able towill be able tocould possiblymay possibly
A: You really should see a doctor about that cough.
B: I know, I probably should. I'll book an appointment this week.
A: Do I have to wear a suit to the interview?
B: You don't have to, but I'd recommend it, it makes a good impression.
A: Where's James? He's late again.
B: He must have got stuck in traffic, he's usually very punctual.
A: Could I possibly leave a bit early today?
B: Of course, that's fine. Is everything alright?
A: You mustn't tell anyone about this, it's confidential.
B: Of course, I understand. I won't say a word.
A: I should have called you earlier, I'm sorry.
B: It's okay, don't worry about it. I wasn't waiting for anything urgent.
A: Could you possibly send me the report by tomorrow?
B: I should be able to, yes. I'll do my best.
A: That can't be right, the numbers don't match.
B: You're right, let me check it again.
A: Shall we get started?
B: Yes, let's. We've got a lot to cover today.
23. Reading Practice
Reading: "Office Rules and Reality"
When Daniel started his new job, his manager explained the rules clearly. "You must badge in every morning," she said, "and you mustn't share your access card with anyone else, that's a serious security issue." However, she also reassured him about flexibility. "You don't have to come in before 9:30 if you've got a good reason, we trust our staff." Daniel appreciated this. He could have worked at a stricter company, but he was glad he hadn't. A few weeks in, he noticed something odd: a colleague always arrived exactly at 9am and left at exactly 5pm, never staying a minute longer. "She must really value her free time," Daniel thought. He later learned she had two young children and had to collect them from school, that explained it. "I should have guessed that," he admitted to himself. "I shouldn't have assumed it was just about the job."
Comprehension Questions
1. What is Daniel not allowed to do with his access card?
2. Does Daniel have to arrive before 9:30?
3. What deduction does Daniel make about his colleague, and is it correct?
4. What does Daniel realise about his assumption?
Show Answers
1. He mustn't share it with anyone else.
2. No, he doesn't have to.
3. He thinks she "must really value her free time", this turns out to be incorrect; the real reason was childcare.
4. He realises he shouldn't have assumed and should have guessed the real reason.
24. Listening Script
ESL Listening Script: "Giving Advice"
Sam: I've got a job interview tomorrow and I'm really nervous.
Priya: You should prepare some answers tonight, that always helps with nerves.
Sam: Good idea. Do I have to bring anything specific?
Priya: You don't have to, but I'd bring a copy of your CV just in case. You never know.
Sam: True. What if they ask a question I can't answer?
Priya: Honestly, you mustn't panic if that happens. You could just say you'll think about it and come back to it. Interviewers respect that more than guessing badly.
Sam: That's reassuring, thanks. I think I'll be okay.
Priya: You will! You've prepared well, you should feel confident.
Listening Questions
1. What does Priya suggest Sam do tonight?
2. Does Sam have to bring anything specific?
3. What should Sam do if he can't answer a question?
Show Answers
1. Prepare some answers.
2. No, he doesn't have to, but it's recommended to bring a CV.
3. He could say he'll think about it and come back to it.
25. Writing Tasks
Task 1, Giving Advice
Write a short paragraph (100 words) giving advice to a friend about a problem, using at least five different modal verbs.
Show Model Answer
I think you should talk to your manager directly about the issue, it might feel uncomfortable, but it could really help in the long run. You don't have to do it immediately; you could wait until your next one-to-one meeting if that feels more natural. You mustn't let it build up too much, though, as that can make things worse. If it doesn't improve after that, you may want to consider speaking to HR. You shouldn't feel like you have to handle this entirely on your own.
Task 2, Rules and Regulations
Write a short set of rules (100 words) for a workplace or public space, using must, mustn't, have to, and don't have to.
Show Model Answer
All visitors must sign in at reception upon arrival. You mustn't bring food or drink into the laboratory at any time, this is a strict safety requirement. Staff have to wear protective equipment when working in designated areas. You don't have to book the meeting rooms in advance for short, informal discussions, but longer meetings require a reservation. Visitors must be accompanied by staff at all times while on site. You don't have to wear a visitor badge if you are a regular contractor, provided you have your ID card.
26. Speaking Tasks
Discussion Questions
What rules must you follow at your job or school?
What advice would you give someone starting a new job?
Describe something you should have done differently in the past.
What skills can you do well? What can't you do yet?
What do you think might happen in your country in the next ten years?
Role Play: Workplace Rules
Practise explaining workplace rules to a new colleague, using must, mustn't, have to, don't have to, and should.
Cambridge Speaking-Style Questions
What rules do you have to follow at home?
What should people do to stay healthy?
IELTS Speaking-Style Questions
Describe a rule you think should be changed. Why?
What advice would you give to someone visiting your country for the first time?
27. Exercises
A. Gap Fill, Choose the correct modal (30 questions)
1. I ___ speak three languages. (ability)
2. You ___ smoke here, it's forbidden. (prohibition)
3. You ___ come if you don't want to, it's optional. (no obligation)
4. She ___ be tired, she's been working all day. (confident deduction)
5. That ___ be true, it's impossible. (confident negative deduction)
6. ___ I open the window? (polite permission)
7. You ___ see a doctor about that. (advice)
8. I ___ studied harder. (past regret)
9. It ___ rain later, the forecast isn't sure. (possibility)
10. She ___ finish the report by Friday. (strong obligation, external rule)
11. I ___ swim when I was five. (past general ability)
12. He ___ have left already, his coat is gone. (confident deduction)
13. You ___ apologise to her, it would be the right thing to do. (advice)
14. ___ we go now? (suggestion)
15. I ___ help you if you'd asked earlier. (past possibility, didn't happen)
16. You ___ worry, everything is fine. (advice, calming)
17. They ___ have missed the train. (uncertain past possibility)
18. I was finally ___ finish the marathon. (past specific achievement)
19. You ___ have spent so much money. (criticism of past action)
20. ___ I help you with that? (offer)
21. Visitors ___ sign in at reception. (rule/obligation)
22. You ___ bring food into the lab. (prohibition)
23. She ___ be at home, her car isn't there. (confident negative deduction)
24. I ___ possibly be late tomorrow. (polite uncertain possibility)
25. You ___ to wear a uniform at this school. (external obligation)
26. We ___ have called ahead, the restaurant was full. (past regret)
27. ___ you help me carry this? (request)
28. He ___ be able to come after all, his plans changed. (future ability)
29. You ___ tell anyone, it's a secret. (prohibition)
30. I ___ rather stay home tonight. (preference)
Show Answers (A)
1. can 2. mustn't 3. don't have to 4. must 5. can't 6. May/Could 7. should 8. should have 9. might/may/could 10. has to 11. could 12. must 13. should 14. Shall 15. could have 16. don't have to / needn't 17. might/may/could 18. able to 19. shouldn't 20. Shall/Can 21. must 22. mustn't 23. can't 24. might 25. have 26. should 27. Could/Can 28. will 29. mustn't 30. would
B. Mustn't or Don't Have To? (15 questions)
1. You ___ park here, it's a fire exit.
2. You ___ come to the party if you're busy, it's totally fine.
3. Students ___ use phones during the exam.
4. You ___ pay now, you can pay later if you prefer.
5. Staff ___ enter the server room without authorisation.
Show Answers (B)
1. mustn't 2. don't have to 3. mustn't 4. don't have to 5. mustn't
C. Error Correction (20 questions)
1. I can to swim.
2. She cans speak French.
3. Do you can help me?
4. I don't can swim.
5. I should studied harder yesterday.
6. I must of left my keys at home.
7. He oughts to apologise.
8. She has to studies every day.
9. That mustn't be true.
10. He musts finish by Friday.
Show Answers (C)
1. I can swim.
2. She can speak French.
3. Can you help me?
4. I can't swim.
5. I should have studied harder yesterday.
6. I must have left my keys at home.
7. He ought to apologise.
8. She has to study every day.
9. That can't be true.
10. He must finish by Friday.
28. Mini Quiz
29. Exam Focus, Cambridge, IELTS, Trinity, SELT
Exam
How Modals Are Tested
Sample Question
Cambridge A2 Key
Basic can/can't for ability; must/mustn't for simple rules.
"You ___ run in the corridor." (mustn't)
Cambridge B1 Preliminary
Should/shouldn't for advice; have to/don't have to.
Multiple choice cloze testing obligation vs advice distinction.
Cambridge B2 First
Key word transformation tests must/have to, mustn't/don't have to extensively.
"It isn't necessary to bring your passport." โ "You ___ bring your passport." (don't have to/needn't)
Use of English: select the correct modal for confident deduction.
IELTS
Modals tested in Speaking (advice, possibility) and Writing Task 2 (recommendations, hedged arguments).
"What advice would you give to...?" requiring should/could/might.
Trinity GESE/ISE (SELT)
Can for ability is core at A1; obligation and advice modals tested from A2 upwards.
"What can you do in your free time?" "What should new arrivals know about the UK?"
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Exam tip
The mustn't vs don't have to distinction is one of the single most frequently tested modal verb points across every exam board, because it tests genuine comprehension rather than memorisation. Make sure you can explain, not just use, the difference before any speaking or writing exam.
30. Frequently Asked Questions
A group of auxiliary verbs (can, could, may, might, must, shall, should, will, would) that express ability, permission, obligation, possibility or deduction.
Subject + modal + base form of the verb, with no "to" and no -s ending, regardless of subject.
"Mustn't" means it is forbidden. "Don't have to" means it is not necessary, but you are still allowed to if you want.
"Must" often implies the speaker's personal authority or strong feeling. "Have to" often implies an external rule or requirement. In everyday speech they are often used interchangeably.
"Can" expresses present ability or informal permission. "Could" expresses past general ability or more polite permission/requests.
For a single specific past achievement, especially involving effort or difficulty, "was/were able to" is more accurate than "could," which is better for general past ability.
Modal + have + past participle. Example: "should have studied," "must have left," "could have helped."
It expresses regret or criticism about a past action that didn't happen: "You should have called me" means you didn't call, and that was a mistake.
No, "should of" is never correct in writing. It comes from the sound of "should've" in speech, but the correct written form is "should have."
May, might and could all express roughly 50% possibility: "It might rain later."
"Must" for confident positive deduction ("She must be tired"), "can't" for confident negative deduction ("That can't be true"), and might/may/could for uncertain deduction.
English uses "can't" for confident negative deduction, not "mustn't," which is reserved for prohibition: "That can't be true," not "That mustn't be true."
They mean almost the same thing, advice or recommendation. "Ought to" is slightly more formal and less common in everyday speech.
Both express around 50% possibility. "May" is slightly more formal; "might" is slightly more common in everyday speech and sometimes suggests slightly less certainty.
No, standard English doesn't combine two modals directly ("will can" is incorrect). Use a substitute form instead: "will be able to."
Mainly used for suggestions and offers in British English: "Shall we begin?" It is rarely used for simple future prediction today.
"Could you...?" and "Would you mind...?" are more polite than "Can you...?" "Could you possibly..." is particularly common and natural in British English.
A formal British modal meaning "it is not necessary": "You needn't worry" = "You don't need to worry."
Yes, invert the modal and subject directly, with no "do/does": "Can you help me?" not "Do you can help me?"
"Could have" notes a missed opportunity relatively neutrally. "Should have" carries stronger criticism or expectation that wasn't met.
Yes, for repeated past actions (not states): "Every summer, we would visit my grandparents." See our Past Simple guide for the comparison with "used to."
No, "have to" is a semi-modal that conjugates normally (has to, does she have to) unlike true modals, which never change form.
Stressing the modal itself changes emphasis: "You COULD do it" (encouraging, emphasising possibility) vs normal unstressed use.
Yes, "can" for ability is core from A1, with obligation and advice modals tested from A2 level upwards in Trinity GESE and ISE Speaking.
Practise giving advice, discussing rules, and making deductions about everyday situations, these naturally require a wide range of modals. Use the exercises in Section 27, then book a free consultation for personalised speaking practice.
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