There is no such thing as "should of" in English grammar.
"It's one of these ones" is funny, I have never heard it before. lol ...but I don't think it's wrong, I think it just puts a little extra attention there. Maybe someone is pointing to something.
I suspect where this of vs. have thing got started was people like me who use the contraction.
Could've
Would've
Should've
People hear that and their brains fill in of instead of 've. If I speak at a normal pace and say could've and could of, unless I exaggerate 'of', it sounds exactly the same.
Could've
Would've
Should've
People hear that and their brains fill in of instead of 've. If I speak at a normal pace and say could've and could of, unless I exaggerate 'of', it sounds exactly the same.