SEMAINE 27 – JOUR 1 Grammar + Listening Thème : Modals of Probability

À la fin de cette leçon, tu seras capable de :

✅ exprimer une forte certitude

✅ exprimer une possibilité

✅ exprimer une faible probabilité

✅ exprimer une impossibilité

✅ faire des déductions logiques

Mon Coach Pro · Grammaire B1–B2

Modals of Probability

Making Deductions & Expressing Possibilities

1. What Are Modals of Probability?

Modals of probability are used to express how certain or uncertain you are about something. Instead of stating a fact, you express your deduction, possibility or conclusion based on evidence.

Structure : Subject + modal + base verb (present)
Subject + modal + have + past participle (past deduction)

The modal you choose shows your level of certainty.
2. The Certainty Scale

Each modal expresses a different level of certainty — from near certain to almost impossible.

MUST
~95% certain ✅
SHOULD
~80% expected
COULD / MAY
~50% possible
MIGHT
~30% less certain
CAN'T / COULDN'T
~5% near impossible ❌
3. MUST — Near Certain Positive Deduction

Use must when you are almost certain something is true based on evidence. It is a logical conclusion.

Present deduction : Subject + must + base verb
Past deduction : Subject + must have + past participle
Konan has been studying for 12 hours. He must be exhausted.
Konan étudie depuis 12 heures. Il doit être épuisé. (conclusion logique)
She passed the BAC with 18/20. She must have studied very hard.
Elle a eu 18/20 au BAC. Elle a dû beaucoup travailler.
Look at that crowd! The concert must be amazing.
Regarde cette foule ! Le concert doit être incroyable.
💡 Key difference : MUST for obligation ("You must wear a seatbelt.") vs MUST for deduction ("He must be tired.") — context makes the difference. Deduction MUST is never followed by an obligation context.
4. CAN'T / COULDN'T — Near Certain Negative Deduction

Use can't or couldn't when you are almost certain something is NOT true — the opposite of must.

Present deduction : Subject + can't + base verb
Past deduction : Subject + can't/couldn't have + past participle
He just ate a huge meal. He can't be hungry again already!
Il vient de manger énormément. Il ne peut pas avoir faim déjà !
She left only five minutes ago. She can't have arrived yet.
Elle est partie il y a seulement cinq minutes. Elle ne peut pas encore être arrivée.
That can't be Aminata — she is in Bouaké this week.
Ce ne peut pas être Aminata — elle est à Bouaké cette semaine.
⚠️ Don't confuse :
CAN'T (prohibition) : "You can't park here." → it's forbidden
CAN'T (deduction) : "That can't be right." → I'm almost certain it's false
5. MIGHT / MAY / COULD — Expressing Possibility

Use might, may, or could when something is possible but uncertain. They express different degrees of possibility.

Present possibility : Subject + might/may/could + base verb
Past possibility : Subject + might/may/could have + past participle
She isn't here yet. She may be stuck in traffic.
Elle n'est pas encore là. Elle est peut-être bloquée dans les embouteillages.
I'm not sure about the meeting time. It might start at 9 or at 10.
Je ne suis pas sûr de l'heure de la réunion. Elle commence peut-être à 9h ou à 10h.
He didn't answer. He could have been sleeping when you called.
Il n'a pas répondu. Il dormait peut-être quand tu as appelé.
She might have forgotten about the meeting — let's remind her.
Elle a peut-être oublié la réunion — rappelons-le-lui.
💡 Nuance :
MAY = slightly more formal, slightly more probable than might
MIGHT = less certain, more tentative
COULD = one of several possibilities
In everyday English, these three are often used interchangeably.
6. SHOULD — Expressing Expectation

Use should when you expect something to be true based on what is normal, planned or logical.

Present expectation : Subject + should + base verb
Past expectation : Subject + should have + past participle
I sent the package three days ago. It should arrive today.
J'ai envoyé le colis il y a trois jours. Il devrait arriver aujourd'hui.
He studied all week. He should pass the exam easily.
Il a étudié toute la semaine. Il devrait facilement réussir l'examen.
The results should have been published yesterday — I wonder what happened.
Les résultats auraient dû être publiés hier — je me demande ce qui s'est passé.
7. Present vs Past Deductions — Full Comparison
ModalPresent deductionPast deduction
MUSTHe must be at home.He must have left early.
CAN'TThat can't be true.She can't have said that.
MIGHTShe might be sleeping.She might have missed the bus.
MAYHe may be busy now.He may have forgotten.
COULDIt could be a mistake.It could have been worse.
SHOULDIt should work fine.It should have worked.
8. Real-Life Contexts — Examples from Côte d'Ivoire
✅ MUST (almost certain) :
Adjoua hasn't eaten since this morning. She must be very hungry by now.
Kouamé got 19/20. He must have prepared really well for the BEPC.
MIGHT/MAY (possible) : The teacher isn't here yet. She might be stuck in traffic on the boulevard.
CAN'T (impossible) : That can't be Konan's score — he never fails English!
COULD HAVE (past possibility) : He didn't show up. He could have forgotten about the appointment.
9. Common Mistakes to Avoid
He must be tired because he studied. He mustn't be wrong. ✔ He can't be wrong. (negative deduction = can't, not mustn't)
→ MUSTN'T = prohibition ("you must not"). CAN'T = near certain it's not true.
She might have forgot the keys. ✔ She might have forgotten the keys. (modal + have + past participle)
→ After modal + have, always use the past participle, not the base verb.
He could be have left already. ✔ He could have left already. (modal + have + past participle — no "be")
→ Past deduction structure : modal + HAVE + past participle. Never insert "be" between have and the participle.
🎓

Coach Assoa vous conseille :

Pour maîtriser les modaux de probabilité, mémorisez d'abord la paire clé : must (presque sûr que oui) ↔ can't (presque sûr que non). Ensuite, ajoutez might/may/could pour le doute.

Entraînez-vous en regardant autour de vous et en faisant des déductions : "That person must be a teacher — she's carrying many books." C'est la meilleure façon d'intégrer ces structures naturellement !

📝 Exercise — Modals of Probability

Test your knowledge of must · can't · might · may · could · should

  • ❓  12 questions
  • ⏱️  15 minutes
  • ✅  Immediate correction after each answer
  • 📊  Score by modal at the end
🎓 Modals of Probability — Mon Coach Pro
15:00
QUESTION 1 / 12
MUST

🏁 Results

📊 Score by modal

📋 Answer Review