How to Use Can, Could and Be Able To - English Modal Verbs for Ability

Hello, I'm Oli.

Welcome to Oxford Online English.

In this lesson, you can learn about using modal verbs to express ability.

If you don't know what modal verbs are, or why you should care about them, watch this

lesson, which gives you an introduction to the topic.

So in this lesson, we're going to focus on using the verbs 'can' and 'could' to talk

about ability.

You will also learn about the verbs 'be able to' and 'managed to'.

These verbs are not modal verbs, but we can't use 'can' or 'could' in every situation to

talk about ability, so we sometimes need to use a different, non-modal verb.

First of all, let's look at using 'can' and 'could' to talk about ability.

You can use 'can' to talk about abilities in the present or the future.

For example: "She can speak Spanish very well."

Or: "Can you come with us on Saturday?"

You can also use 'could' to talk about general abilities in the past.

For example: "I could run much faster when I was younger."

'When I was younger' is a general ability, so I could run faster any time I wanted.

"She could play the violin when she was a child."

Again, this is a general ability about a longer period in the past.

This is quite simple, and I'm sure you're familiar with it.

However, there are many situations where you can't use 'can' or 'could' to talk about ability,

and we need to use a different verb.

One of these verbs is 'be able to'.

Generally, 'can' and 'be able to' have the same meaning.

So, you can usually use either verb without any difference in meaning: "She can speak

Spanish very well," or: "She's able to speak Spanish very well."

These two sentences have the same meaning.

"I could run much faster when I was younger," or: "I was able to run much faster when I

was younger."

Again, there's no difference in meaning between these two sentences.

However, you can't use 'can' or 'could' in every verb tense.

If you want to use, for example, the present perfect form, there's no form of 'can' or

'could' which you can use.

So in these cases, you need to use a form of 'be able to'.

For example: "He's been able to swim since he was two years old."

There's no way to use 'can' or 'could' in this sentence and keep the same meaning.

We have to use 'be able to'.

"I like being able to choose my own working hours."

After the verb 'like', we need a verb with '-ing', so we need to use 'be able to'.

Again, there's no way to use 'can' or 'could' in this sentence.

There are many cases like this.

Generally, if you have a choice, it's better to use 'can' or 'could', because it makes

your sentence simpler and shorter.

We sometimes choose to use 'be able to', even when 'can' or 'could' are possible, because

it sounds more formal.

OK, now let's look at ability in the past: 'could' vs. 'be able to'.

This gets a little bit more complicated.

Let's look at an example sentence: "The traffic was really bad, but we could catch our train."

Does it sound right to you?

What do you think?

If you said it sounds wrong, you're actually correct; this sentence is not right, it's

not possible.

Do you know why?

The answer is this sentence is talking about a specific ability at a specific moment in

the past.

In this case, you can't use 'could'; you need to use a different verb.

You could say: "The traffic was really bad, but we were able to catch our train."

Or: "The traffic was really bad, but we managed to catch our train."

In both of these sentences, we're talking about one moment, one train.

It's a specific situation; that means we can't use 'could'; we must use 'be able to' or 'managed

to'.

Let's look at some more examples.

"It was hard work, but we managed to finish everything on time."

That means we finished something specific, at a specific moment.

"Our car broke down on the way, but luckily I was able to fix it."

I fixed it at a specific moment; it wasn't a general thing.

There's one more important point here, which makes it even a little bit more complicated.

This difference between general and specific situations only applies to positive sentences.

If your sentence is negative, there's no difference between 'could' and 'be able to'.

It's like most other cases: you can choose which verb to use and it doesn't matter.

"It was hard work, and we couldn't finish everything on time."

Or: "It was hard work, and we weren't able to finish everything on time."

Because these sentences are negative, it doesn't matter if the situation is general or specific;

it's now possible to use both forms: 'couldn't' or 'weren't able to'.

Again, there's no difference in meaning in this case.

So, to review, 'can/could' or 'be able to' generally have the same meaning, unless you're

talking about a specific situation in the past, and the sentence is positive.

If you're not sure about this, remember you can always use 'be able to' in every case

and never be wrong.

Next, let's look at 'could' in more detail.

'Could' has two meanings.

Look at two sentences: "I couldn't help you because I had too much to do."

"I couldn't help you even if I wanted to."

In these two sentences, the verb 'could' is used in different ways.

Can you see the difference?

Here's a question to check your understanding: how would you use 'be able to' in these two

sentences?

If you want to think about your answer, pause the video and think about it.

In the first sentence, "I couldn't help you because I had too much to do," the meaning

is past.

If we use 'be able to', we would say: "I wasn't able to help you because I had too much to

do."

In the second sentence, 'could' has a hypothetical or conditional meaning.

To use 'be able to', we would say, "I wouldn't be able to help you even if I wanted to."

So 'could' can have two different meanings; a past meaning and a hypothetical meaning.

You need to use the context of the sentence or the situation to understand what 'could'

means.

For example: "Why couldn't he do it last week?"

The time marker 'last week' shows you that this sentence is past, and that 'could' has

a past meaning.

"We could work together, if you wanted."

Again, the end of the sentence with 'if' shows you that 'could' has a hypothetical meaning.

OK, let's review the important points from this lesson.

You can use 'can' or 'could' to talk about abilities in the past, present or future.

'Can/could' and 'be able to' usually have the same meaning.

Sometimes you need to use 'be able to', for example if you need to use a verb with '-ing',

or if you need to use the present perfect tense, or some other tense where 'can/could'

don't exist.

In the past, 'could' and 'was/were able to' are sometimes different.

If you are talking about a specific situation, and the sentence is positive, you can only

use 'was/were able to', or 'managed to'.

Finally, 'could' can have two different meanings.

It can have a past meaning, the same as 'was/were able to', or it can have a hypothetical meaning,

like 'would be able to'.

OK, that's the end of the lesson.

I hope it was useful for you.

If you want to see the full version of this lesson, you can check it out on our website.

The full lesson includes a text, so you can read and review everything.

There's also a quiz to help you practise the topic and check that you've understood everything.

OK, that's all.

Thanks again for watching, and I'll see you next time.

Bye bye!