Grammar › Modal Verbs › Can, Could & Be able to
Can, Could & Be able to
'Can', 'could' and 'be able to' all talk about ability. Choose by time and form:
- Can — present ability and possibility (She can drive).
- Could — past general ability and polite requests (I could read at four; Could you wait?).
- Be able to — when you need an infinitive or perfect form (I want to be able to swim).
For a single successful action in the past, use 'was/were able to' or 'managed to', not 'could': I was able to fix it.
How to use can, could and be able to
| Meaning | Form | Example |
|---|---|---|
| Present ability / possibility | can + base verb | She can speak three languages. |
| Past general ability | could + base verb | I could run fast as a child. |
| Polite request | Could you…? | Could you open the window? |
| Infinitive / perfect forms | be able to | I’d love to be able to ski. |
Modals like can and could never change form (he can, she can) and are always followed by the base verb with no to.
When to use each
1. Can — present ability and possibility
- I can swim, but I can’t dive.
- You can pay by card here. (it’s possible / allowed)
2. Could — past ability and polite requests
- At five, she could read whole books. (general past ability)
- Could you help me for a second? (polite request)
3. Be able to — the missing forms
- I want to be able to cook properly. (after another verb)
- I haven’t been able to reach him all day. (perfect tense)
⚠️ Typical error: for one successful past action, use was/were able to or managed to: We were able to book a table — not
we could book a table.
Common mistakes
1. Adding ‘to’ after can/could. I can to swim → I can swim.
2. Adding -s for he/she. She cans drive → She can drive.
3. Using ‘could’ for one past success. I could pass the exam → I was able to pass the exam.
✏️ Practice: Can, Could & Be able to
1. My sister ___ speak four languages.
2. When I was young, I ___ climb trees easily.
3. ___ you pass me the salt, please?
4. I'd love ___ play the guitar.
5. The exam was hard, but I ___ finish in time.
6. She ___ drive; she failed her test twice.
7. I ___ reach you all morning — your phone was off.
8. Choose the correct version of: 'He can plays the piano.'
9. We ___ get tickets at the last minute — we were lucky!
10. Choose the sentence about GENERAL past ability.
11. Fill in the gap
When I was five, I ___ swim. (ability)
Type one word.
12. Correct the mistake
She cans drive a bus.
Type the whole corrected sentence.
13. Fill in the gap
I tried hard and finally ___ to open the door. (one success)
Type two words.
Frequently asked questions
What is the difference between 'can' and 'be able to'?
They mean the same for present ability, but 'be able to' has forms 'can' lacks — after another verb (want to be able to) and in perfect tenses (have been able to).
When can't I use 'could' for the past?
For one specific successful action, use 'was/were able to' or 'managed to': I was able to catch the train (not 'I could catch').
Is 'can' or 'could' more polite for requests?
'Could' is a little more polite and less direct: Could you help me? is softer than Can you help me?
Does 'can' change with he/she/it?
No. Modals have one form: he can, she can — never 'he cans'.
👩🏫 For teachers
CEFR objectives for “Can, Could & Be able to”:
- Can use 'can' for present ability and possibility (CEFR A2).
- Can use 'could' for past general ability and polite requests.
- Can use 'be able to' in infinitive and perfect forms, and 'was able to' for single past actions.
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