Possibility in the past

Dusan StojilkovicI could've done better.(but I didn't)

I had the ability to do better. (but I didn't)

Dusan StojilkovicI couldn't have done that without you.

It would not have been possible for me to do that without your help. (but it was possible because you helped)

This is a more of less standard fo

So, should I always use couldn't have when I want to talk about every possibility in the past?

Dusan StojilkovicSo, should I always use couldn't have when I want to talk about every possibility in the past?

I can't answer "yes" because of the underlined words above. There are always exceptions.

I think a better procedure would be to post a few sentences with "could have" and/or "couldn't have" that you think follow this rule that

Now I think I understand this perfectly.

Anyway here are some sentences:

I could've danced all night. ( But I didn't dance all night)
I couldn't have danced all night. ( I didn't have ability, so I didn't do it)

He might've left some papers on the table. ( The papers might be on the table, might not)

Am I right about this?

Dusan StojilkovicHe might've left some papers on the table. ( The papers might be on the table, might not)

It is possible that he left some papers on the table. Yes. So they might be there now - or might not.

Dusan StojilkovicI could've danced all night. ( But I didn't dance all night)
I couldn't have danced all night. ( I didn'

So, basically could have means that I had ability.

But when I say: I could have danced all night.- The first thing that come up on my mind is the missed opportunity in the past.

Jim, when I want to say that I didn't do something in the past can say like this: I could've screamed yesterday. - I missed the opportunity in the past. Do I have to say: I could've screamed yesterday, but I didn't.

?

Dusan Stojilkovicwhen I want to say that I didn't do something in the past

Just say I didn't do it.

To focus on the fact that you had the ability to do so, but did not use your ability to do so:

I could have (done it), but I didn't.

The scenario is a bit unusual for talking about missed opportunities. Let's try somethi

Okay. I understand that.

But, these kind of sentences make me confused: Dorian couldn't read when he was four.

Dorian couldn't have read when he was four.

We can use 'couldn't have' to talk about something we were not capable of doing.

Dusan StojilkovicDorian couldn't read when he was four. ... Dorian couldn't have read when he was four.

Here is my interpretation of these two sentences.

1. Dorian was not able to read when he was four. You could put a book in front of him and ask him to read, but you would not get any results. Dorian would just sit there, book in hand, with no ide