Collins Cobuild

participle.
You could have given it all to me.
You know, she could have done French.
You often use this form when you want to express disapproval about
something that was not done.
You could have been a little bit tidier.
You could have told me!
6
 You  use  ‘could  not  have’  or  ‘couldn’t  have’  followed  by  a  past

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participle to say that it is not possible that someone had the ability to
do something.
I couldn’t have gone with you, because I was in London at the time.
She couldn’t have taken the car, because Jim was using it.
7
In most cases, you can choose to use ‘can’ or ‘be able to’. However, you
sometimes have to use ‘be able to’. You have to use ‘be able to’ if you
are using another modal, or if you want to use an ‘-ing’ form, a past