WRONG:

COULD OF, SHOULD OF, WOULD OF

RIGHT:

COULD HAVE, SHOULD HAVE, WOULD HAVE

This is one of those errors typically made by a person more familiar with the spoken than the written form of English. A sentence like "I would have gone if anyone had given me free tickets" is normally spoken in a slurred way so that the two words "would have" are not distinctly separated, but blended together into what is properly rendered "would've." Seeing that V tips you off right away that "would've" is a contraction of "would have." But many people hear "would of" and that's how they write it. Wrong.

List of errors