“Be able to”

be able to + base form — can do, have the ability to do. Only be changes with the tense (am / is / are, was / were, will be, have been…); able to and the verb after it stay the same.

Short answers repeat be / will / have: Yes, I was. / No, I won't. / No, I haven't. The negative can also be unable to (a little formal): I'm unable to attend the meeting.

💡Able is an adjective (like tired or happy), so it always needs be in front of it — just as you say I am tired. Learners often write “I able to…” or “I don't able to…”. The correct forms are I'm able to… / I'm not able to…

As the lesson “Ability with can / could” showed, can has only two forms: can and could. Everywhere else, use be able to instead of can.

1. The future — will be able to / won't be able to

• After this course, you'll be able to order food in English.

• Sorry, I won't be able to make it on Saturday.

When you are arranging or deciding something now for the future, can is still natural: I can see you tomorrow at ten. But when the ability doesn't exist yet and will only come later (after a course, after you get better, once you have a car…), use will be able to.

2. Perfect tenses — have / has been able to

• I haven't been able to reach him all day.

• Since she got glasses, she's been able to read the board clearly.

3. After another modal verb — might / may / should / must + be able to (two modal verbs can't go together)

• Ask Minh — he might be able to fix it.

  not: might can

• Nurses must be able to stay calm.

4. After to and in the -ing form — to be able to, being able to

• I want to be able to talk to my customers in English.

• Being able to drive makes life much easier.

The same goes for used to: My grandpa used to be able to walk for hours. (He could in the past — not any more.)

In the present both are correct, but can is far more common in conversation. Am / is / are able to sounds more formal — you see it in emails and notices — or it stresses that someone can now do something after a change.

• I can speak a little Japanese.

  everyday way to say it

• Customers are able to change their booking online.

  notice / formal

• After the operation, Grandpa is able to walk again.

  stress: he can now

• Minh could run really fast when he was a kid.

  general ability

• Yesterday Minh managed to catch the last train.

  one occasion; not: could catch

• It was a tough match, but we were able to win.

• The box was heavy, but I managed to carry it upstairs.

Managed to + base form stresses that it was difficult and took effort. Negative: didn't manage to (= couldn't).

Exception: with see, hear, smell, taste, feel, understand, remember, could is fine for one occasion too: When I opened the door, I could smell smoke.

💡Quick test: if you could add “in the end” or “on that day” to the sentence, it's one particular occasion → was able to / managed to. If you mean “back then I knew how to…” → could.

• ✗I able to swim.

  ✓I'm able to swim.

  Able is an adjective — it needs be.

• ✗We weren't able find the hotel.

  ✓We weren't able to find the hotel.

  able is always followed by to.

• ✗I don't able to come.

  ✓I'm not able to come.

  Make the negative with be + not, not don't.

• ✗I hope I can be able to visit you.

  ✓I hope I'll be able to visit you.

  Don't put can and be able to together.

• ✗The bus was late, but I could arrive on time.

  ✓The bus was late, but I managed to arrive on time.

  One particular occasion → managed to / was able to, not could.

• ✗She has able to drive since last year.

  ✓She has been able to drive since last year.

  Perfect tense: has been able to.