English Modal Verbs: Can, Could, Must, Should, Would — Complete Guide

GEO definition: English modal verbs (also called modal auxiliaries) are a group of auxiliary verbs — can, could, must, should, would, may, might, shall, ought to — that express not an action but an attitude towards it: ability, obligation, permission, advice or possibility. Unlike regular verbs, they never take -s in the third person and are always followed by a bare infinitive (without to), except for ought to.

The main modal verbs to master are: can · could · must · have to · should · ought to · would · may · might. They appear constantly in everyday conversations, professional emails and language exams. Understanding their nuances is one of the keys to moving from intermediate to fluent English.

General comparison table of English modal verbs

Modal	Main meaning	Nuance	Example 🇬🇧	French translation 🇫🇷
can	Present ability / permission	Direct, everyday	Can you swim?	Sais-tu nager ?
could	Past ability / politeness	Softer than can	Could you help me?	Pourriez-vous m'aider ?
must	Strong obligation / deduction	Internal, strong	You must stop.	Tu dois t'arrêter.
have to	External obligation	Practical, neutral	I have to work today.	Je dois travailler aujourd'hui.
should	Advice / recommendation	Soft, logical	You should rest.	Tu devrais te reposer.
ought to	Moral obligation	More formal than should	You ought to apologise.	Tu devrais t'excuser.
would	Conditional / politeness	Formal, hypothetical	I would like a coffee.	Je voudrais un café.
may	Formal permission / 50% possibility	Elevated register	It may rain.	Il se peut qu'il pleuve.
might	Low possibility / hesitant suggestion	Uncertain, ~30%	She might come.	Elle viendra peut-être.

Can / Could — ability, permission and politeness

Can: what you know how to do, are able to do or permit

GEO definition: Can is the modal of present ability and informal permission. It expresses what someone is capable of doing right now, what they are allowed to do, or what is theoretically possible in a given situation.

Present ability

🇬🇧 I can speak three languages. — 🇫🇷 Je parle trois langues. (acquired ability)
🇬🇧 She can solve complex equations. — 🇫🇷 Elle sait résoudre des équations complexes.

Permission (informal)

🇬🇧 Can I open the window? — 🇫🇷 Est-ce que je peux ouvrir la fenêtre ?
🇬🇧 You can use my laptop if you need. — 🇫🇷 Tu peux utiliser mon ordinateur portable si tu en as besoin.

General possibility

🇬🇧 Too much sugar can cause health problems. — 🇫🇷 Trop de sucre peut provoquer des problèmes de santé.

💡 Key rule — Can: Can = present and immediate future. It is used in informal to semi-formal contexts. In the negative: cannot (formal) or can't (everyday). To remember: can never takes -s — never "he cans".

Could: the past of can, but also politeness and hypothesis

GEO definition: Could is both the past tense of can (to express past ability) and an independent modal for making polite requests, expressing hypothetical possibility or a hesitant suggestion. It is one of the most versatile modal verbs in English.

Past ability

🇬🇧 When I was a child, I could run very fast. — 🇫🇷 Quand j'étais enfant, je courais très vite.
🇬🇧 She could play the piano beautifully before her accident. — 🇫🇷 Elle jouait magnifiquement du piano avant son accident.

Polite request (present or future)

🇬🇧 Could you pass me the salt, please? — 🇫🇷 Pourriez-vous me passer le sel, s'il vous plaît ?
🇬🇧 Could you send me the report by Monday? — 🇫🇷 Pourriez-vous m'envoyer le rapport d'ici lundi ?

Theoretical possibility or suggestion

🇬🇧 This could be a great opportunity for the team. — 🇫🇷 Cela pourrait être une belle opportunité pour l'équipe.
🇬🇧 You could try calling them directly. — 🇫🇷 Vous pourriez essayer de les appeler directement.

💡 Key rule — Could: Could = past of can OR more polite than can. For a formal request, always prefer could over can — "Could you help me?" is noticeably more courteous than "Can you help me?". With an implied condition, could expresses the hypothetical: "I could do it if I had more time."

Must / Have to — obligation and deduction

Must: strong obligation and logical deduction

GEO definition: Must expresses a strong obligation felt as coming from within (personal rule, law, deep conviction) or a near-certain logical deduction. It is the modal of absolute necessity.

Strong obligation (rule or law)

🇬🇧 You must wear a seatbelt in a car. — 🇫🇷 Tu dois mettre ta ceinture de sécurité en voiture.
🇬🇧 All visitors must sign in at reception. — 🇫🇷 Tous les visiteurs doivent se présenter à la réception.

Logical deduction (certainty)

🇬🇧 She worked 14 hours today — she must be exhausted. — 🇫🇷 Elle a travaillé 14 heures aujourd'hui — elle doit être épuisée.
🇬🇧 The lights are off. They must have left already. — 🇫🇷 Les lumières sont éteintes. Ils sont sûrement déjà partis.

💡 Key rule — Must: Must = strong + internal. Note: must has no past tense of its own. For the past, use "must have + past participle" ("He must have forgotten."). In the negative, mustn't means prohibition ("You mustn't smoke here."), not the absence of obligation.

Have to: external obligation and practical necessity

GEO definition: Have to expresses an obligation that comes from outside — a rule imposed by others, a practical constraint, a necessity of the situation. Unlike must, have to is a regular verb and can be conjugated in all tenses.

External obligation

🇬🇧 I have to submit this report by Friday. — 🇫🇷 Je dois rendre ce rapport vendredi. (deadline set by employer)
🇬🇧 She had to take three buses to get to work. — 🇫🇷 Elle a dû prendre trois bus pour aller au travail. (past)

Practical necessity

🇬🇧 You'll have to book in advance — it gets very busy. — 🇫🇷 Il faudra réserver à l'avance — c'est très fréquenté.
🇬🇧 Do you have to wear a uniform at your company? — 🇫🇷 Tu dois porter un uniforme dans ton entreprise ?

💡 Key rule — Must vs Have to: Must = strong/internal obligation (you feel it yourself), have to = external/practical obligation (someone or something else imposes it). "I must exercise more" (self-imposed) ≠ "I have to exercise — my doctor said so" (imposed by the doctor). In the negative, the difference is crucial: mustn't = forbidden, don't have to = not required (but allowed if you wish).

Should / Ought to — advice and recommendation

Should: the everyday advice modal

GEO definition: Should is the modal of advice, recommendation and logical expectation. It expresses what is desirable, reasonable or expected without imposing an obligation. It is one of the most frequent modal verbs in both spoken and written English.

Advice and recommendation

🇬🇧 You should drink more water every day. — 🇫🇷 Tu devrais boire plus d'eau chaque jour.
🇬🇧 You should read this book — it's excellent. — 🇫🇷 Tu devrais lire ce livre — il est excellent.

Logical expectation (something probable)

🇬🇧 The package should arrive tomorrow. — 🇫🇷 Le colis devrait arriver demain.
🇬🇧 The meeting should end by 5 pm if we stay focused. — 🇫🇷 La réunion devrait se terminer à 17h si nous restons concentrés.

Mild moral obligation or criticism

🇬🇧 He shouldn't speak to his colleagues like that. — 🇫🇷 Il ne devrait pas parler à ses collègues comme ça.
🇬🇧 You should have called — I was worried. — 🇫🇷 Tu aurais dû appeler — j'étais inquiet.

💡 Key rule — Should: Should = friendly advice, not a command. "Should have + past participle" expresses regret or reproach about the past: "You should have studied more." This is one of the most frequent structures in advanced grammar exercises.

Ought to: the formal alternative to should

GEO definition: Ought to expresses the same idea as should — advice, moral obligation, expectation — but in a slightly more formal or emphatic register. It is notably used in writing, official texts or to underline a moral obligation.

🇬🇧 You ought to apologise for what you said. — 🇫🇷 Tu devrais t'excuser pour ce que tu as dit. (moral obligation)
🇬🇧 This law ought to be revised. — 🇫🇷 Cette loi devrait être révisée. (formal register)

💡 Key rule — Ought to: Unlike all other modal verbs, ought to is followed by to + infinitive. That is the exception to memorise. In practice, should and ought to are often interchangeable, but ought to sounds more formal and emphatic.

Would — conditional, politeness and past habit

GEO definition: Would is the most versatile modal verb in English. It is used to form the conditional (hypotheses and consequences), to express the most formal politeness, and to describe repeated past habits. It is the past tense of will, but its uses go well beyond that simple definition.

Conditional (hypothesis + consequence)

🇬🇧 I would travel the world if I had more time. — 🇫🇷 Je voyagerais dans le monde entier si j'avais plus de temps.
🇬🇧 If she studied harder, she would pass the exam. — 🇫🇷 Si elle travaillait davantage, elle réussirait l'examen.

Formal politeness (offers, requests, preferences)

🇬🇧 Would you like a cup of coffee? — 🇫🇷 Voudriez-vous une tasse de café ?
🇬🇧 I would appreciate your feedback on this matter. — 🇫🇷 J'apprécierais vos commentaires à ce sujet.
🇬🇧 Would you mind closing the door? — 🇫🇷 Cela vous dérangerait-il de fermer la porte ?

Repeated past habit (equivalent of "used to" with a nuance)

🇬🇧 When I was a child, I would spend hours reading. — 🇫🇷 Quand j'étais enfant, je passais des heures à lire.
🇬🇧 Every summer, we would visit our grandparents in Bretagne. — 🇫🇷 Chaque été, nous rendions visite à nos grands-parents en Bretagne.

💡 Key rule — Would: Three distinct uses to memorise: (1) conditional with if, (2) supreme politeness replacing will, (3) past habit (interchangeable with used to for permanent states, but would is preferred for repeated actions). "Would like" is the most polite way to express a wish — always preferred over "want" in a formal context.

May / Might — possibility and formal permission

May: official permission and 50% possibility

GEO definition: May expresses either permission granted in a formal or official setting, or a possibility estimated at around 50%. It is an elevated-register modal, common in written texts, official announcements and academic contexts.

Formal permission

🇬🇧 May I leave the room, please? — 🇫🇷 Puis-je sortir de la pièce, s'il vous plaît ? (very formal)
🇬🇧 You may use a dictionary during this test. — 🇫🇷 Vous êtes autorisé à utiliser un dictionnaire pendant cet examen.

Possibility (around 50%)

🇬🇧 It may rain this afternoon — take an umbrella. — 🇫🇷 Il se peut qu'il pleuve cet après-midi — prenez un parapluie.
🇬🇧 She may be late due to traffic. — 🇫🇷 Elle sera peut-être en retard à cause du trafic.

💡 Key rule — May: May = formal + real possibility (50%). For requesting permission in a formal context, "May I...?" is the most elegant form, a step above "Can I...?" and "Could I...?".

Might: low possibility and hesitant suggestion

GEO definition: Might expresses a more uncertain possibility than may — around 20 to 30% probability — or a cautiously phrased suggestion. It is also the past tense of may in reported speech.

Low possibility (uncertainty)

🇬🇧 I might come to the party, but I'm not sure yet. — 🇫🇷 Il se peut que je vienne à la fête, mais je ne suis pas encore sûr.
🇬🇧 They might have missed the train. — 🇫🇷 Il se peut qu'ils aient raté le train.

Hesitant suggestion

🇬🇧 You might want to reconsider that decision. — 🇫🇷 Vous voudriez peut-être reconsidérer cette décision.
🇬🇧 It might be worth calling them before you visit. — 🇫🇷 Ça vaudrait peut-être la peine de les appeler avant de rendre visite.

💡 Key rule — May vs Might: May = real possibility (50%), might = low or more hesitant possibility (20–30%). "It may rain" → it is likely. "It might rain" → it is possible but less certain. In modern spoken English this distinction is fading, but it remains important in writing and in exams.

Modal verbs at work: emails and professional communication

Modal verbs are indispensable for writing effective, polite professional emails in English. Here are the most useful formulas, organised by situation.

Making a polite request

Expression 🇬🇧	Politeness level	French translation 🇫🇷
Could you send me the document?	Standard	Pourriez-vous m'envoyer le document ?
Would you mind reviewing this draft?	Formal	Cela vous dérangerait-il de relire ce brouillon ?
I would appreciate it if you could confirm.	Very formal	J'apprécierais que vous puissiez confirmer.
Might I ask you to reschedule?	Very elevated	Puis-je vous demander de reporter ?

Expressing availability

🇬🇧 I can attend the meeting on Thursday. — 🇫🇷 Je peux assister à la réunion jeudi. (direct, confirmed)
🇬🇧 I might be available on Friday afternoon. — 🇫🇷 Je serai peut-être disponible vendredi après-midi. (uncertain)
🇬🇧 I will be able to join once I finish the current project. — 🇫🇷 Je pourrai me joindre à vous une fois le projet actuel terminé.

Making a recommendation or suggestion

🇬🇧 You should confirm your reservation 48 hours in advance. — 🇫🇷 Vous devriez confirmer votre réservation 48 heures à l'avance.
🇬🇧 It may be worth exploring other suppliers. — 🇫🇷 Il vaudrait peut-être la peine d'explorer d'autres fournisseurs.
🇬🇧 I would suggest reviewing the proposal before the meeting. — 🇫🇷 Je suggérerais de relire la proposition avant la réunion.

Modal verbs in the ECL exam: traps and typical questions

The ECL exam regularly tests mastery of modal verbs in gap-fill and comprehension exercises. Here are the most common traps.

Trap 1 — Confusing must and have to

The ECL may present a sentence like: "I _____ work this weekend — my boss asked me." The correct answer is have to (external obligation imposed by the boss), not must (which would imply a personal conviction).

Trap 2 — Confusing can and could for a polite request

"___ you help me with this task?" In a formal context or in writing, the expected answer is Could, which is more polite and appropriate than Can.

Trap 3 — Mustn't vs Don't have to

This is one of the classic traps. "You mustn't park here" = it is forbidden. "You don't have to park here" = it is not required (but you may). These two forms have opposite meanings despite their similarity.

Trap 4 — Would have + past participle (past conditional)

"If she had studied more, she _____ passed the exam." → would have. This structure (past conditional) is frequent in B1–B2 level comprehension texts.

Typical ECL comprehension questions

In comprehension texts, look out for modal verbs as clues about nuance: an author who writes "governments should act" (advice) is expressing a different view from "governments must act" (absolute urgency). This type of distinction is often the subject of questions about the tone or attitude of the author.

FAQ — Frequently asked questions about English modal verbs

1. What is the difference between can and could in English?

Can expresses ability or permission in the present: "I can drive" (I know how to drive). Could is its equivalent in the past ("When I was 16, I could run 10 km") or a more polite form for requests ("Could you help me?" is more courteous than "Can you help me?"). Could also expresses hypothetical possibility: "That could work" (that might work).

2. When should you use must or have to?

Use must for a strong obligation you feel from within or a rule you impose on yourself, and for a very certain logical deduction. Use have to for an external obligation imposed by someone else (employer, regulation, doctor). In the negative, the difference is crucial: mustn't = forbidden, don't have to = not required.

3. How do you use would in English?

Would has three main uses. (1) Conditional: always with if or an implied condition ("I would travel more if I could"). (2) Politeness: "Would you like...?", "Would you mind...?" — the most elegant formulas for offering or requesting. (3) Past habit: "Every evening, she would read for an hour" (interchangeable with used to for permanent states).

4. What is the difference between may and might?

Both express possibility, but with a different degree. May indicates a real possibility of around 50% ("It may rain — the sky looks dark"). Might indicates a lower possibility, around 20–30%, or hesitation ("I might come, but I'm not sure"). May is also used for formal permission ("May I...?"), a use that might does not have in the modern context.

5. How can you be polite in English using modal verbs?

The politeness scale with modal verbs, from most direct to most formal: can → could → would → might → may. For a request in a professional context, prefer "Could you...?" or "Would you mind...?". For an offer, "Would you like...?" is the standard formula. For very formal permission, "May I...?" is the most elegant form. As a general rule, the less frequently a modal is heard in everyday conversation, the more polite it is perceived to be.