'Could' is past of 'can', and it shows ability to do something. For example, "I could not assist him." However, I have a doubt on its use when it's compared with using "did not", as in following sentence:

It was raining yesterday, so we could not go out.

It was raining yesterday, so we did not go out.

I had to chose one of the above-mentioned sentences since this was asked as a multiple choice question in my job test (Q. No. 35):

job test question

About the use of "could not" I have also seen Cambridge Dictionary using "could not" in somehow a similar manner.

Cambridge Dictionary's sentence on using "could"

The difference between the job test question and Cambridge Dictionary's example sentence lies in the first clause, it was raining (shows past progressive) and the bank had closed (implies past perfect).

Pondering further over the question, the use of "could not" and "did not" might also seem confusing for native learners when it comes to using the conjunction "so" prior to "could not" or "did not." However I am not sure, but I do know the meaning of "so" as to give reason to something happened, happening, or will happen.

meaning of "so"

  • 2
    Both are correct, but they mean different things. Strictly speaking, all four options can be correct in different contexts.
    – alphabet
    Jul 10, 2023 at 2:43
  • @alphabet Does that mean the job test question is fallible?
    – Ahmed
    Jul 10, 2023 at 2:45
  • 3
    @Ahmed The question is nonsensical. I think its authors may not have good English skills themselves.
    – alphabet
    Jul 10, 2023 at 2:48
  • 3
    In rare circumstances, "will not" or "shall not" might also make sense: "We must not go to the event today if there's even a slight chance of rain. It was raining yesterday, so we will not go out today."
    – alphabet
    Jul 10, 2023 at 3:00
  • 1
    The Cambridge sentence could just as well have read "The banks were closed...", corresponding with "It was raining". Both could not and did not are equally valid; it depends whether the rain made the planned outdoor activity impossible, or the speaker simply chose not to travel somewhere in the rain. Jul 10, 2023 at 8:43

1 Answer 1


In question 35, B would be the right answer. They are all gramatically correct, but only one of them actually makes sense in a realistic scenario.

  1. It was raining yesterday, so [we will not go] out. As "will" is in the present, it means you refuse to go out now, because it rained yesterday. That would be illogical

  2. It was raining yesterday, so [we did not go] out. "did not" is a choice, you didn't want to get wet, so you did not go out.

  3. It was raining yesterday, so [we shall not go] out. "Shall" is used for commands, Thou shall not kill fx. And as it's still worded as in the present, it would essentially be you commanding (your kids?) that they can't go outside, because it rained yesterday.

  4. It was raining yesterday, so [we could not go] out. Could not is used when there is an external force preventing us from doing something, not just because of our own decisions (example with the closed banks, fx. even if you go to the bank, there is no way to get money. unlike if the bank was open, but you just didn't go. You could have gotten money, you just chose not to get any) This would be a logically false statement, as the rain isn't stopping you from leaving the house.

It should be mentioned, that in common speak it wouldn't be unusual to use the phrase "I can't leave the house, it's raining" Even if it is technically false, it is commonly understood we don't like getting wet from the rain, and therefore are "compelled" to stay inside.

  • 1
    "Can't" doesn't mean "is physically prevented from." Using "can't" in this context is perfectly correct.
    – alphabet
    Jul 10, 2023 at 18:37

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