CAN vs COULD — Comparaison Complete

Toutes les differences entre CAN et COULD expliquees

1. Vue d'ensemble

Critere	CAN	COULD
Temps	Present	Passe / Conditionnel / Poli
Certitude	Plus certain	Moins certain
Politesse	Neutre / informel	Plus poli / formel
Negation	can't / cannot	couldn't / could not
Question	Can + S + V ?	Could + S + V ?

2. Capacite (Ability)

CAN — Present

I can swim.

= Je sais nager (maintenant).

She can speak three languages.

= Elle parle trois langues (actuellement).

COULD — Passe

I could swim when I was five.

= Je savais nager quand j'avais 5 ans.

She could speak Italian as a child.

= Elle parlait italien quand elle etait enfant.

Attention : COULD pour la capacite au passe ne s'utilise que pour des capacites generales et durables. Pour un evenement specifique reussi, utilisez was/were able to ou managed to : "After three attempts, I was able to pass the test." (pas "I could pass").

3. Permission

CAN — Informel

Can I use your phone?

= Est-ce que je peux utiliser ton telephone ?

Usage : entre amis, en famille, collegues proches.

COULD — Plus poli

Could I use your phone?

= Pourrais-je utiliser votre telephone ?

Usage : avec des inconnus, superieurs, contexte formel.

4. Demandes (Requests)

Niveau de politesse	Structure	Exemple
Informel	Can you...?	Can you open the door?
Poli	Could you...?	Could you open the door?
Tres poli	Could you possibly...?	Could you possibly open the door?
Tres formel	Would you mind...?	Would you mind opening the door?

5. Possibilite

CAN — Possibilite generale

It can rain a lot in November.

= Il peut pleuvoir beaucoup en novembre. (c'est une realite generale)

Certitude : fait etabli, possibilite reelle.

COULD — Possibilite incertaine

It could rain tomorrow.

= Il pourrait pleuvoir demain. (ce n'est pas sur)

Certitude : hypothetique, moins probable.

Degre de certitude	Modal	Exemple
Certain (90%+)	must / will	It must be true.
Probable (70%)	should / ought to	It should work.
Possible (50%)	can / could / may / might	It could happen.
Peu probable (20%)	might	It might work, but I doubt it.

6. Suggestions et propositions

CAN — Proposition directe

We can go to the cinema tonight.

= On peut aller au cinema ce soir. (suggestion confiante)

COULD — Suggestion plus douce

We could go to the cinema tonight.

= On pourrait aller au cinema ce soir. (c'est une idee parmi d'autres)

7. Le conditionnel avec COULD

COULD s'utilise dans les phrases conditionnelles (type 2 — ireel du present) :

Structure	Exemple	Sens
If + passe, S + could + V	If I had more time, I could* learn Chinese.*	Si j'avais plus de temps, je pourrais apprendre le chinois.
If + passe, S + could + V	If she were here, she could* help us.*	Si elle etait la, elle pourrait nous aider.
S + could + V + if...	I could* come if you invited me.*	Je pourrais venir si tu m'invitais.

8. COULD HAVE + participe passe

Pour parler d'une capacite ou possibilite non realisee dans le passe :

Phrase	Sens
I could have* helped you.*	J'aurais pu t'aider (mais je ne l'ai pas fait).
She could have* won the race.*	Elle aurait pu gagner la course (mais elle n'a pas gagne).
We couldn't have* done it without you.*	Nous n'aurions pas pu le faire sans toi.
They could have* warned us.*	Ils auraient pu nous prevenir (reproche).

COULD HAVE = regret ou reproche. C'est une structure tres courante pour exprimer le regret ("I could have studied harder") ou le reproche ("You could have told me!").

9. Tableau recapitulatif complet

Usage	CAN	COULD
Capacite presente	I can swim.	—
Capacite passee	—	I could swim at age 5.
Permission informelle	Can I leave?	—
Permission polie	—	Could I leave?
Demande informelle	Can you help?	—
Demande polie	—	Could you help?
Possibilite reelle	It can happen.	—
Possibilite incertaine	—	It could happen.
Suggestion directe	We can try.	—
Suggestion douce	—	We could try.
Conditionnel	—	I could help if...
Regret / reproche	—	I could have helped.

10. Exercices

A. Choisissez CAN ou COULD :

1. you speak English when you were ten? (passe)

2. I borrow your pen? (poli, present)

3. She swim — she learned last summer. (present)

4. It be true, but I'm not sure. (possibilite incertaine)

5. We go to Italy this summer. What do you think? (suggestion)

1. Could (passe) — 2. Could (demande polie) — 3. can (capacite presente) — 4. could (incertain) — 5. could (suggestion douce)

B. Completez avec COULD HAVE + verbe :

1. You (tell) me earlier! I waited for nothing.

2. She (win) the competition, but she was injured.

3. We (take) a taxi instead of walking in the rain.

4. He (be) a great doctor, but he chose music instead.

1. could have told — 2. could have won — 3. could have taken — 4. could have been

C. Traduisez en anglais :

1. Pourrais-je avoir l'addition ? →

2. Quand j'etais jeune, je pouvais courir vite. →

3. On pourrait aller au restaurant ce soir. →

4. Tu aurais pu m'appeler ! →

5. Si j'avais de l'argent, je pourrais voyager. →

1. Could I have the bill? — 2. When I was young, I could run fast. — 3. We could go to a restaurant tonight. — 4. You could have called me! — 5. If I had money, I could travel.