Can, could, be able to: Ability and possibility

Grammar / B1 Grammar lessons and exercises \ Can, could, be able to: Ability and possibility

✏️ Exercises

Can, Could, Be Able To: Ability & Possibility

Grammar chart comparing 'can', 'could', and 'be able to' for ability, possibility, permission, requests, and sense verbs. Designed for B1 English learners.

🟦Ability

Use can / could to describe ability. Use can’t / couldn’t for inability.

  • She could play the piano very well.
  • Children can’t concentrate for long periods.
  • I can speak Chinese.

🟩Possibility

Use can to talk about general or specific possibilities.

  • Anyone can win this competition.
  • I can’t come to the party next week.

🟪Permission

Use can / could to give or ask for permission.

  • You can’t smoke in the house, but you can smoke on the terrace.
  • Can I come in?

🟨Requests

Use can / could to make polite requests.

  • Can you help me?
  • Could you speak more slowly, please?

🟥See, Smell, Hear, Feel, Taste

These are stative verbs — use can, NOT continuous form.

❌ Are you hearing that?
✅ Can you hear that?

❌ I’m smelling gas!
✅ I can smell gas!

🟦Be Able To

Similar to can, but more formal. Required for non-present/past tenses.

  • They are able to do the job faster.

❗ Must use “be able to” for:

  • ✅ I’d like to be able to visit her more often. (infinitive)
  • ✅ I like being able to talk with friends. (-ing form)
  • ✅ Will we be able to talk after the concert? (future)
  • ✅ I haven’t been able to study. (present perfect)

⬛Can/Could vs Be Able To — Specific Situations

✅ General Ability

  • She can speak five languages.
  • My son could walk at 11 months.
  • She’s able to speak five languages.

✅ Specific Past Achievement

❌ There was a fire, but they could escape.
✅ They were able to / managed to escape.

❌ He could find the place.
✅ He was able to / managed to find it.

✅ Negative Specific Situations

It was dark, and they couldn’t find the exit. → Also correct: weren’t able to find it.

📌 Remember:
Can / Could = ability, possibility, permission, requests
Be able to = formal alternative; required for infinitive, -ing, perfect, future forms
⚠️ For sense verbs (see, hear, smell...) → always use can, never continuous
🔁 In negative past specific situations → both couldn’t and wasn’t able to are acceptable
❗ For positive past specific achievements → use was/were able to or managed to, NOT “could”