English Grammar
CAN - COULD - BE ABLE TO: difference and use
'Can' and 'could' are used to express possibility, ability and permission as well as offers or requests.
'Be able to' is used to express ability and often replaces 'can' in this function.
Here are some examples of their use:
| CAN | COULD |
|---|---|
| Possibility: • You can exchange it if it doesn't suit. • All our products can be ordered online. Ability: • All the children can read and write. • The old lady is blind. She can’t see. Permission: • Can I borrow your pen? (or ‘may’ I) • Can I take one of these brochures? Offers: • Can I help you? • Can I get you something to drink? |
Possibility: • What he says could be true – who knows! • We could order a pizza if it’s not too late. Ability: • I could run much faster when I was young. • My grandfather could imitate bird sounds. Permission: • Could I use your phone please? • Could I leave a little early today? Requests: • Could you post this letter for me please? • Could you ask him to call me back? |
BE ABLE TO |
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Ability: • He is competent and able to deal with difficult customers. • I’m not able to reach the top shelf. It's too high for me. • She's very clever. She was able to decipher the code. • The little boy isn’t able to tie his shoe laces. • The injured soldier is not able to walk without crutches. • The old lady was not unconscious so she was able to call for help. • The doctor was able to understand what she was saying. • Is the old man able to look after himself? |
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see also: modal verbs
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