"Can" vs. "Able to" in the English grammar

Can vs. Able to

'Can' and 'be able to' are both used to refer to abilities. In this lesson, we will learn their differences and when to use them.

"Can" vs. "Able to" in the English grammar

What Is Their Main Difference?

'Can' and 'be able to' are both used to show ability but the main difference between them is in their parts of speech. 'Can' is a modal verb and 'be able to' is a phrasal verb.

'Can' is one of the most commonly known modal verbs (also known as modals or modal auxiliary verbs) used to talk about possibilities, ask for or give permissions, request something, etc. We use can to refer to the present and the future. Have a look:

I can talk about my favorite movie all day.

I can stay overtime tomorrow.

Be able to

'Be able to' is a verb phrase. We use 'be able to' to talk about abilities. The presence of the auxiliary verb 'be' allows us to use the phrase in both present and past tense.

He was able to jump really high.

He is able to jump really high.

Similarities

Talking about Abilities

We use 'can' and 'be able to' to talk about abilities, knowledge, or talent. We use 'can' to talk about the present and the future. 'Be able to' is used in all tenses to show ability. For example:

I can teach English.

I was able to teach English.

I am able to teach English.

I will be able to teach English.

Negation

When we want to make negative sentences, we use 'cannot' and 'not able to' or 'unable to.' For instance:

I cannot teach English.

I am not able to teach English.

I am unable to teach English.

Differences

Parts of Speech

'Can' is a modal verb that is used to give additional information about the function of the main verb. Have a look:

I can ride a bicycle.

They can whistle.

'Be able to' is a phrasal verb. A phrasal verb is a phrase that functions as a verb. Take a look at the following example:

I am able to ride a bicycle.

They are able to whistle.

With Modals

'Can' is a modal verb and we cannot use two modals in one sentence at once. In this case, we use 'to be verb' since we can use it with other modals. Have a look:

I should can work with a broken keyboard.

I should be able to work with a broken keyboard.

With Tenses

We use 'can' and 'be able to' with tenses:

Past Tense

We cannot use 'can' itself to talk about the past. Instead, we use 'could.' With 'be able to,' we use the past tense of the auxiliary verb 'be': was/were. Take a look at the following example:

I can run fast when I was younger. → I could run fast when I was younger.

I was able to run fast when I was younger.

Present Tense

We can use both 'can' and 'be able to' to talk about present abilities. 'Can' is more common than 'be able to.' Here are some examples:

Harry can play multiple sports.

Harry is able to play multiple sports.

Future Tense

We use 'be able to' to talk about a future skill to have in the future. These skills are not available right now and will only be achieved in the future. For example:

I will be able to see again after the operation.

I can see again after the operation.

Here, we are talking about the present rather than the future.

We use both 'can' and 'be able to' to talk about decisions for the future and future arrangements. Have a look:

I can give you a hand tomorrow.

I will be able to give you a hand tomorrow.

Questions

Both 'can' and 'be able to' are used to make questions.
'Can' is simply inverted to create questions. Watch:

I can swim. → Can I swim?

You can make an example. → Can you make an example?

To make a question with 'be able to,' we invert the 'be' and do not change the position of 'able to.' Consider the following examples:

He is able to jump high enough. → Is he able to jump high enough?

They are able to make it to the meeting. → Are they able to make it to the meeting?

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