Could of, would of, should of
I admit, most writers don’t let this slip-up in spoken English affect their written work but since half the Internet these days is written by people who don’t strive to monitor their English, mistakes like this come up all the time.
Could of, would of and should of are not correct and should never be used. Could have, would have and should have are correct.
‘We could have shared the duties,’ Sarah said.
‘I would have done that!’ the boy exclaimed.
‘It should have been me!’ Alex complained.
In their contracted forms, these sentences would look like this.
‘We could’ve shared the duties,’ Sarah said.
‘I would’ve done that!’ the boy exclaimed.
‘It should’ve been me!’ Alex complained.
The only reason could of exists is because of pronunciation. When spoken fast, could have and could’ve sounds very similar to could of.
To cut a long story short, however, could of, would of, should of and any other examples including of taking the place of have is incorrect, and hopefully always will be.