I learned that native English speakers sometimes won't use "could" and place "was able to" instead.

I read answers to the similar questions to mine, and now I guess it's about whether

  1. the sentence indicates the subject's efforts or circumstances

  2. the sentence indicates one occasion or not

  3. the sentence indicates possibility or not

I think I can say "I could use English to communicate with Maria because she was an English speaker" because it's not about my efforts, but about a situation.

Also, I cannot say "I could speak better English in the class yesterday" because it's about my effort, and also it's about an occasion.

And I cannot always say "People there could understand me well" instead of "People there were able to understand me well" because "could" here indicates possibility or it might be indirect expression.

Might that be right?

(I revised my question title.)

  • 1
    No, I'm afraid not. There is no reason why you can't use could in your second sentence, and in the other two you can use either. Jul 27, 2022 at 13:30
  • 1
    There are definitely times to avoid "could" as a past tense. "We could meet yesterday" sounds weird to me. "were able to" would sound much better. I don't know why.
    – cruthers
    Jul 27, 2022 at 14:11

1 Answer 1


When used by itself, could generally means the same thing as be able to. However, could takes on a completely different meaning when you use it with a past participle. Because of this, I don't think your criteria are relevant (or even valid).

You use past modal verbs with a past participle to talk about things that really didn't happen in the past. These include could have, should have, might have and would have. To be able to is not hypothetical.

Could have means that something was possible -- you were able to do it -- but you didn't:

I could have used English to communicate with Maria because she was an English speaker.

...but you didn't use English to communicate with Maria; you spoke in Spanish.

I was able to use English to communicate with Maria because she was an English speaker.

This did happen -- you used English. It's not hypothetical.

I could have spoken better English in class yesterday.

...but I didn't. Maybe I was tired or just didn't feel like it.

I wasn't able to speak better English in class yesterday.

Something prevented me from doing it, so I could not do it and it did not happen. It's not hypothetical.

People there could understand me.

This is something different altogether because you're not using a past participle. There's nothing special about this sentence. It's about the past, so it's the past tense. You can also say:

People there were able to understand me.

The context might determine which you choose, but both are perfectly acceptable and, for all intents and purposes, interchangeable.

If you want to make it hypothetical, you can say:

People there could have understood me, but they just didn't pay attention.

People there could have understood me, but they just weren't paying attention.

  • Thank you for your answer! But I didn't use a past participle in any of my examples. I hear that sometimes there are occasions where you should always use "was able to" and not "could".
    – Nigutumok
    Jul 28, 2022 at 8:10
  • I thought "could" by itself can be hypothetic in some sentences like "Perhaps Maria could help me."
    – Nigutumok
    Jul 28, 2022 at 8:22
  • @Nigu8tumok. Sorry, I must have misunderstood. In your second example, you can't say that without using a participle (it's incorrect the way you wrote it). I guess there were a number of issues and I tried to highlight several. I can delete my answer if it's not appropraite. Jul 28, 2022 at 9:12
  • Thank you for your help! My second example is for explanation of the fact that I cannot use "could" there. I write with a lot of mistakes, I am sorry for my not clear sentences. Well, are issues about my mistakes in sentences?
    – Nigutumok
    Jul 28, 2022 at 9:20
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    You can't use could that way in the past tense. For example, you can say "Perhaps Maria could help me." but you have to say "Perhaps Maria could have helped me." when you're talking about the past. It's probably because the outcome is not determined in the first example, where it's strictly hypothetical in the second because it's over. She didn't help you. Jul 29, 2022 at 21:10

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