Modals of Ability: can, could, be able to

Modals of Ability express ability in the past, present, and future using can, could, and be able to. It’s important to understand when each is appropriate and why some situations allow more than one correct option. If you need something more simple, start with Can and Can’t.

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Modals of Ability Table
Present Ability
Past Ability
Future Ability
Exercises on Modals of Ability

Modals of Ability Table

Modal	When to Use	Example
Can	To talk about present ability.	She can play the guitar very well.
Could	To talk about past ability.	When I was 10, I could climb trees easily.
Be (un)able to	To express ability in different tenses (past, present, future).	He will be able to fix the car tomorrow.

The modal verbs ‘can’ and ‘could’ are also used as modals of Prohibition and Permission, Deduction and Probability and Advice when we want to be more polite. Click the links to check it out. Now about Ability, let’s break it down to Present, Past, and Future.

Present Ability

“Can” is more common in speech. “Be able to” is often used for formal or academic contexts.

Modal	Use	Example
can	current general ability	She can play the piano.
am/is/are able to	also for current ability, usually more formal or written	She is able to speak German, English, and French.

Can and Can’t – a beginner’s guide

Past Ability

Here what matters most is context: “could” is not usually used for specific one-time success.

Modal	Use	Example
could	general past ability	When I was a child, I could swim.
was/were (un)able to	specific achievement in the past	We were able to fix the car yesterday.

Remember: Use “could” for something you were usually or always able to do. Use “was/were able to” for something you managed to do once ,or in a particular situation. Here are other examples:

Sentence	Best Choice	Explanation
I could swim when I was five.	General ability	A skill you had over time.
After training for months, I was able to swim across the lake.	Specific success	One-time achievement.
She could read before starting school.	General ability	Long-term skill.
Despite the snow, we were able to catch the bus.	Specific situation	One instance.

Depending on the sentence and context, “could” is about possibility, not ability. If we say “We can reach the top of the mountain before sunset” implies an ability to do so.
In contrast, “We could reach the top of the mountain before sunset” implies a possibility. Read more about it in Modals of Deduction and Probability.

Future Ability

Note that ‘can’ is not usually used for future ability, except with hope, permission, or informal tone.

Modal	Use	Example
can	informal tone a hope for the future	I hope we can visit Morocco next summer.
will be able to	future ability	I will be able to join the meeting in 10 minutes.

Exercises on Modals of Ability

EXERCISE: Write a complete sentence with Modals of Ability

Write complete sentences with Modals of Ability. Use the words in bold as indicated.
Example:
Prompt: she – play the piano – beautifully (affirmative – can)
Answer: She can play the piano beautifully.

1 / 10

They – finish – the test in time yesterday (negative – be able to)

2 / 10

He – fix – the computer yesterday (affirmative – be able to)

3 / 10

I – swim – very well (affirmative – can)

4 / 10

We – find – the place (negative – can)

5 / 10

I – lift – this box (negative – be able to)

6 / 10

She – walk – without help last month (negative – could)

7 / 10

They – come – to the party next week (affirmative – can)

8 / 10

He – solve – the problem on his own (negative – can)

9 / 10

She – speak – three languages (affirmative – be able to)

10 / 10

We – run – faster last year (affirmative – could)

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More exercises: PerfectEnglish | Learnenglish | TestEnglish | LiveWorksheets1 | LiveWorksheets2

Check other groups of Modals here:

Modals of Obligation and Necessity

Modals of Deduction and Probability

Modals of Prohibition and Permission