Should I use could or could have in the following sentences.

I was preparing really hard for the presentation because it could affect/could have affected my future significantly.

At that moment, I knew it could change/could have changed everything.

I was standing in the hallway thinking what could go wrong/could have gone wrong in an hour.

The reason I'm struggling here is that I think could is used for future possibility, not past possibility. But here I'm talking about future in the past, and I want to convey that it was a crucial point and the result could/could have affected my future, without giving away the result of the situation.

1 Answer 1


The choice depends on the timing of the events in question.

We don't know from your statement whether the presentation has already taken place or whether it still lies in the future. We only know that your preparation for the presentation is past.

Neither do we know whether the future you speak of still lies ahead of you or whether you are looking back many years later on past events.

If the presentation still has the possibility of affecting your future, it could affect things.

If the presentation no longer has the possibility of affecting your future, it could have affected things.

As so often, it all depends on the context.

  • For the last example, let's imagine that I'm saying this the day after the incident. So could have gone wrong is the right choice because I've specified the time "in an hour" which obviously refers back to a finished period of time in the past. Correct?
    – Yuri
    Feb 16, 2020 at 12:16
  • No. In an hour could refer to an hour past or an hour in the future. The logic of my answer still applies. Feb 16, 2020 at 21:22

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