A common mistake is to write ‘could of’ instead of could have or could’ve
I could of told you that.
I could’ve told you that.
The reason for the mistake is that the pronunciation of ’ve is the same as that of of when it is not stressed. This is a common error but it is definitely considered wrong in standard English.
Isn’t “have” either an auxiliary verb or verb and “of” a preposition?
Are these acceptable? If yes, why? If not, why not?
I of heard that story before.
Diane of already gone.
John ofn’t phoned, of he?
I ofn’t visited London before.
Of you seen Roz?
Of she been invited?
They still ofn’t of any news when I spoke to them yesterday.
I don’t know man, Oxford Dictionary (click Grammar Point to expand) says that https://www.oxfordlearnersdictionaries.com/definition/english/have_2