1. How to Use Can and Could to Talk about Ability
You can use can to talk about abilities in the present or the future:
- She can speak Spanish very well
- Can you come with us on Saturday?
You can use could to talk about general abilities in the past:
- I could run much faster when I was younger. = Any time I wanted.
- She could play the violin when she was a child. = She had this ability for a period of time.
This is quite simple, and I’m sure you’re familiar with this. However, there are many situations where you cannot use can or could to talk about abilities, and we need to use a different verb.
2. How to Use Can and Be Able To
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. = She’s able to speak Spanish very well.
- I could run much faster when I was younger. = I was able to run much faster when I was younger.
However, can and could can’t be used in all verb tenses. If you want to use the present perfect (for example), there’s no way to use can or could, so you need to use be able to:
- 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.
- I like being able to choose my own working hours. –> After like we need a verb with -ing, so we need to use be able to—there’s no way to use can or could.
Learn more about talking about working hours and a routine in this OOE lesson: Talking About Your Routine.
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!