Forms and uses of can and could. To be able to.

1. MODAL VERBS 1: CAN/COULD
ABILITY AND POSSIBILITY
Intermediate

2. MODAL VERBS
(1) They are followed by the infinitive without to:
Ex.: I can dance reggaeton really well.
(2) They are not used with auxiliaries in questions or
negatives:
- We use inversion in questions:
Ex.: Can you speak English?
- We add “not” to the verb in negative sentences.
Ex.: Sorry, I can’t (cannot) speak any foreign language.
(3) They are very irregular. To express some tenses we have
to use other expressions (ex.: to be able to)

3. FORMS
• Present: CAN
Ex.: I can speak 15 languages apart from
English.
• Past: COULD
Ex.: I could sing very well when I was young.
• Conditional: COULD
• Ex.: I could help you if I you want.

4. TO EXPRESS OTHER FORMS AND TENSES
• Present perfect:
Ex.: Sorry, I haven’t been able to do the homework
lately. I’m too busy.
• Past perfect:
Ex.: Before the class, he had been able to finish the
homework.
• Future with will:
Ex.: You’ll be able to communicate in England, if you
study English.
• Infinitive: to be able to
Ex.: I’d like to be able to climb the Everest.
• Gerund: being able to
Ex.: I love being able to walk everywhere.

5. USES
• To express ability:
• Ex. I can drive a car.
• To express posibility/impossibility:
• Ex.: Sorry, I couldn’t come to class yesterday,
I was ill.
• To express prohibition:
• Ex: You can’t smoke in class.
• In requests:
• Could I borrow some money?

6. SPECIAL USES
• To be able to can also be used in the present and
past to be more formal:
Ex.: Sorry, I wasn’t able to come to class
yesterday.