We use can to describe an ability and cannot or can’t to describe a lack of ability in the present:
She can speak Spanish but she can’t speak Italian.
If the present ability is surprising or involves overcoming some difficulty, we can also use is/are able to:
Despite his handicap he is able to drive a car.
To emphasise the difficulty or to suggest a great effort (in the present, past or future) we use manage to. In more formal English we can also use succeed in + -ing form:
Do you think she’ll manage to get a visa?
The army succeeded in defeating their enemy.
To describe a future ability we use will be able to:
Will I be able to speak fluently by the end of the course?
We also use be able to where can/could is grammatically impossible, for example:
I haven’t been able to drive since I dislocated my wrist. (with the perfect aspect)
We love being able to talk the local language. (with -ing forms and infinitives)
We use could to describe the possession of an ability in the past:
Mozart could play the piano at the age of five.
To describe the successful use of an ability on a specific occasion we do not use could, but rather, was/were able to:
Mike's car broke down but fortunately he was able to repair it.
But we can use could in questions, and in sentences with limiting adverbs such as only or hardly:
‘Could you fix the computer yourself?’ ‘No, I could only back up the key files.’
She was so exhausted she could hardly speak.
We use couldn’t or was/were not able to to describe a lack of ability or success:
Mozart couldn’t speak French.
Despite being a mechanic, Mike couldn’t fix his car when it broke down yesterday.
2. POSSIBILITY, DEDUCTION AND SPECULATION
3. ARRANGMENTS, SUGGESTIONS, OFFERS
4. ASKING FOR AND GIVING/REFUSING PERMISSION
5. OBLIGATION AND NECESSITY
6. PROHIBITION AND CRITICISM
7. ABSENCE OF OBLIGATION OR NECESSITY
8. RECOMMENDATION AND ADVICE
9. LOGICAL DEDUCTION AND PROBABILITY
10. WILLINGNESS AND REFUSAL
Please log in to read the following part!