Be able to
Definition
Be able to expresses ability or successful achievement. Unlike can, it can be used in a wide range of tense and non-finite forms: was able to, has been able to, will be able to and to be able to.
Examples
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Marta is able to solve the problem.
The present form expresses current ability.
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We were able to find a taxi.
The past form often presents a successful result in a particular situation.
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You will be able to access the file tomorrow.
The future form expresses ability that will exist later.
Can vs. be able to
I can swim.
Can is the usual concise form for present ability.
I have been able to swim since I was six.
The perfect form is possible with be able to, not with can.
Can and be able to overlap in the present, but be able to is required when the grammar needs forms that can does not have.
Past ability can describe either a general skill or a successful event
Could often describes general past ability. Was/were able to is especially common for a successful action in one particular situation.
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As a child, Niko could run very fast.
This describes a general past ability.
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Despite the smoke, Niko was able to reach the exit.
This emphasizes success in a specific situation.
Common mistakes
I will can help tomorrow.
I will be able to help tomorrow.
Can has no infinitive form after will. Use will be able to.
She has could finish the course.
She has been able to finish the course.
Use has been able to for the present perfect.
Quick check
Question 1 of 3
Which sentence correctly expresses future ability?
Future ability uses will be able to + base verb.Which sentence emphasizes success in one past situation?
Were able to open presents a successful action in a specific past situation.Which sentence uses a correct perfect form?
The present perfect form is has/have been able to.Nice work — you've completed the quick check.
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