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. • You can take either bus N° 16 or bus n°18A. • All our products can be ordered online. Ability: • All the children can read and write. • I can carry the box myself - it's not too heavy. • The old lady is blind. She can’t see. Permission: • Can I borrow your pen? (or ‘may’ I) • Can I ask you something? • Can I take one of these brochures? Offers: • Can I help you? • Can I carry that for you? • Can I get you something to drink? |
Possibility: • What he says could be true – who knows! • That parcel could be for me – I'm expecting one. • We could order a pizza if it’s not too late. Ability: • I could run much faster when I was young. • My mother could play the violin. • My grandfather could imitate bird sounds. Permission: • Could I use your phone please? • Could I borrow your bicycle to go to the Post Office? • Could I leave a little early today? Requests: • Could you post this letter for me please? • Could you pass the salt please? • Could you ask him to call me back? |
| BE ABLE TO | |
|
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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