Modal Verbs: Be able to Practice Tests with B1 Grammar Rules & Examples

Modal Verbs: Be Able To

In English, we use be able to to talk about ability — what someone can or cannot do. It works in a similar way to the modal verb can, but be able to is more flexible. We can use it in tenses and situations where can does not work.

Look at these simple examples:

• She is able to speak three languages.
• I was able to finish the exam on time.
• They will be able to travel next summer.

In this lesson, you will learn how to form be able to correctly, when to use it instead of can, and how to avoid common mistakes.

What Does "Be Able To" Mean?

Let's start with a small story.

Marco is learning to drive. Right now, he cannot drive alone. But after his lessons, he will be able to drive. Last year, he was able to ride a motorbike, so he already understands the road rules.

In this story:

• will be able to drive = future ability (something he can do in the future)
• was able to ride = past ability (something he could do in the past)

Be able to expresses ability — the capacity or skill to do something. The verb be changes depending on the tense and the subject (the person or thing doing the action).

How to Form "Be Able To"

The structure is simple:

Subject + correct form of "be" + able to + base verb

The base verb is the verb in its simplest form, with no endings added. For example: speak, run, drive, finish, help.

The verb be changes to match the subject and the tense. Here is how it works across the most important tenses:

Present Simple: Am / Is / Are Able To

Use am / is / are able to to talk about ability in the present — what someone can do now or generally.

Past Simple: Was / Were Able To

Use was / were able to to talk about ability in the past — what someone could do at a specific time or in general in the past.

Future Simple: Will Be Able To

Use will be able to to talk about ability in the future — what someone will be capable of doing later.

Other Useful Tenses with "Be Able To"

Because be able to uses the verb be, we can combine it with many different tenses and structures. Here are some useful examples at B1 level:

Negative Forms of "Be Able To"

To make a negative sentence with be able to, add not after the verb be.

Subject + be + not + able to + base verb

• I am not able to attend the meeting.
• He was not able to find a parking space.
• They will not be able to come to the party.

We often use contractions (short forms) in spoken English and informal writing:

Question Forms of "Be Able To"

To make a question, move the verb be to the beginning of the sentence, before the subject.

Be + subject + able to + base verb?

• Are you able to come on Friday?
• Was she able to speak to the manager?
• Will they be able to deliver it by Monday?
• Is he able to use a computer?

"Be Able To" vs "Can": Important Differences

Both can and be able to express ability, but they are not always interchangeable. Here is when to use each one:

When "Can" and "Be Able To" Mean the Same Thing

In the present simple, you can often use either form with the same meaning:

• I can swim. = I am able to swim.
• She can speak French. = She is able to speak French.

However, be able to often sounds more formal than can.

When You Must Use "Be Able To" (Not "Can")

Can only works in the present and, as could, in the past. It does not have a future form or a perfect form. This is why we need be able to in many situations.

Past Ability: "Could" vs "Was / Were Able To"

This is an important difference at B1 level. Both could and was / were able to talk about past ability, but they are used differently.

Use could for general past ability — a skill or ability someone had over a long period of time:

• When I was young, I could run very fast. (general ability — I had this skill for years)
• She could speak Spanish when she was a child.

Use was / were able to for a specific successful action in the past — something someone managed to do on one particular occasion:

• The firefighters were able to rescue all the people. (they succeeded on this specific occasion)
• Despite the traffic, I was able to arrive on time.

Important note: In negative sentences, you can usually use either couldn't or wasn't / weren't able to for both general and specific situations:

• I couldn't find my keys. ✅
• I wasn't able to find my keys. ✅

Common Mistakes

Here are the most common errors learners make with be able to. Study these carefully!

❌ She is able to speaks three languages.
✅ Always use the base verb (no endings) after "able to". She is able to speak three languages.

❌ I will can help you tomorrow.
✅ Never put two modal verbs together. I will be able to help you tomorrow.

❌ They might can get a refund.
✅ Use "be able to" after another modal verb. They might be able to get a refund.

❌ He was able to swim when he was young. (for a long-term general skill)
✅ Use "could" for general past ability. He could swim when he was young.

❌ The doctors could save the patient. (for one specific successful event)
✅ Use "was / were able to" for a specific past success. The doctors were able to save the patient.

❌ Are you able to speaks English?
✅ Use the base verb after "able to". Are you able to speak English?

❌ She have been able to work since Monday.
✅ Use the correct form of "have" with the subject. She has been able to work since Monday.

Be Able To: Quick Summary

Be able to expresses ability — what someone can or cannot do. Here are the key points to remember:

• The structure is: subject + be + able to + base verb.
• The verb be changes with the subject and tense: am, is, are, was, were, will be, has/have been.
• Use not after be to make negative sentences: is not able to, wasn't able to, won't be able to.
• Move be to the front of the sentence to make questions: Are you able to...? Was he able to...?
• Use be able to (not can) after other modal verbs, in the future, in the present perfect, and with would.
• In the past, use could for general ability and was / were able to for one specific successful action.
• Always use the base verb (no -s, -ed, or -ing endings) after able to.

Now practise modal verbs: be able to in the exercises below.