In a topic about negative structure: negative question, Swan said that a question could ask a confirmation of a negative belief. So, let's look at the following two sentences:

Oh, Dear. Can't they come this evening?


Oh, Dear. Couldn't they come this evening?

The first sentence was provided by Swan, but the second is mine. As far as I understand what Swan said, the first sentence shows the speaker suspects that they didn't come. In contrast, in the second sentence, the speaker shows that it might be good if they come.

Am I correct?

  • 1
    I edited a few minor details but I don't want to change "it might be good if they come" since I'm not sure what you mean to say there.
    – TimR
    Oct 28, 2014 at 13:10
  • If you are asking if your second second constitutes a positive question, it does not. The positive question for the first sentence would be: "Can they come this evening?" The positive question for your question is: "Could they come this evening?"
    – Jim
    Oct 28, 2014 at 14:27
  • @TRomano Is "it might be good if they come" nonsensical? I meant a simialir as "it would perhaps be good if they came". Does one make a sense? Oct 29, 2014 at 18:59
  • It might be good if they come is perfectly fine.
    – Jim
    Oct 30, 2014 at 1:57

2 Answers 2


Let's say you're having company tomorrow morning. Your toilet breaks. Your spouse phones the plumber, and reports that the earliest the plumber can come by is tomorrow afternoon. You can say:

Oh, dear! Couldn't they come this evening?

And you could mean by that, Can you please phone them back and ask if it would be at all possible for them to come today. You could tell them that we would pay extra for the emergency service.

Or you could be having a party, but certain friends do not arrive. You ask a mutual friend why they are not here. Couldn't they come this evening? and you would mean, Did something happen that prevented them from coming?


This is similar to the differences between Can and Could.


Can't they come this evening? Implies it wasn't an option to come. Maybe the car broke down and they had no other transportation.

Couldn't they come this evening? Implies they decided not to come by choice.

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