Free English Lessons
Can, Could, Be Able to – Modal Verbs for Ability – Video
In this free English video lesson, you can learn how to use the modal verbs for ability: can and could. You will also learn about the verbs be able to and managed to to talk about ability. These verbs are not modal verbs, but cannot use can or could in every situation to talk about ability, so sometimes we need to use a different verb.
There are many cases like this. Generally, if you have a choice, it’s better to use can/could, because it makes your sentence simpler.
We sometimes choose to use be able to, even when can/could are possible, because it sounds more formal.
3. How To Use Could and Be Able To to Talk about Ability in the Past
Look at an example sentence:
The traffic was really bad, but we could catch our train.
Does it sound right to you? If not, you’re right—the sentence is not correct.
Do you know why?
The answer is: this sentence is talking about a specific ability in the past.
In this sentence, we’re talking about a specific situation at a specific time. In this case, you can’t use could, we need to use a different verb.
You could say:
The traffic was really bad, but we were able to catch our train.
The traffic was really bad, but we managed to catch our train.
To talk about an ability in a specific situation in the past, use was/were able to or managed to. For example:
It was hard work, but we managed to finish everything on time. –> 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.
You can’t use could in these sentences.
There’s another complication here: this difference between general and specific situations only applies to positive sentences.
In negative sentences, there’s no difference between could and be able to, whether the situation is general or specific:
It was hard work, and we couldn’t finish everything on time.
It was hard work, and we weren’t able to finish everything on time.
Even though this is a specific situation, we can use could because the sentence is negative.
So, to sum up, can/could and be able to generally have the same meaning, unless you are talking about a specific situation in the past, and the sentence is positive.
If you’re not sure about this, remember that you can use be able to in all of these sentences, and never be wrong.
4. The Two Meanings of Could
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 sentences, the verb could is used in different ways.
Can you see the difference?
Here’s a question to check your understanding: how could you use be able to in these two sentences?
I wasn’t able to help you because I had too much to do.
I wouldn’t be able to help you even if I wanted to.
So could can have two 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 could has a past meaning.
We could work together if you wanted –> the end of the sentence …if you wanted shows you that could has a hypothetical meaning.
Let’s review the main points on can, could, be able to from the 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.
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).
Could can have two meanings: past (same as was/were able to) or hypothetical (same as would be able to).
We hope you enjoyed this English video lesson from Oxford Online English!
Modal Verbs For Ability Quiz
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If you have a choice between using can/could and be able to, you should generally use:
be able to
Question 1 Explanation:
It's more common, and it sounds more natural, to use 'can/could' in most sentences if it is possible to do so.
"We weren't able to help them."
Is it possible to use could in this sentence?
Question 2 Explanation:
Although this sentence is about a specific ability at a specific moment in the past, it is also negative, which means using 'could' is possible.
"I could do it by Friday if you gave me some help."
How could you use be able to in this sentence?
I am able to do it by Friday
I was able to do it by Friday
I would be able to do it by Friday
I will be able to do it by Friday
You might need to use a form of be able to if:
You are talking about ability in the future
You want to use a verb tense other than the present/past simple
You are talking about a specific ability in the present
You are writing in formal English
Question 4 Explanation:
You only need to use 'be able to' in two cases: if you are using a verb tense where 'can' can't be used (e.g. the present perfect), or if you are talking about a specific ability in the past. In all other cases, you can choose which to use.
"We weren't able to get hold of him."
"We didn't manage to get hold of him."
Do these sentences have the same meaning, or are they different?
They are the same
They are different
You might choose to use be able to, even when can/could are possible, in order to:
Show you are talking about a specific moment
Show you are talking about the future
Sound more formal
Sound more conversational
The verb can can be used to talk about:
The present only
The present or the future
The future only
The present or the past
"It was close, but we were just able to finish everything."
Is it possible to use could in this sentence?
Question 8 Explanation:
This sentence is about a specific ability at a specific moment in the past, so 'could' is not possible.
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