The formation of tag questions Sentence + COMMA (,) + a helping verb ( do, don’t, does, doesn’t, did, didn’t, have, haven’t, has, hasn’t, can, can’t, etc .) OR the verb TO BE ( is, isn’t, are, aren’t, was, wasn’t, were, weren’t, etc .) + a pronoun ( I, you, we, they, he, she, it ). Oxford is a school, isn’t it? sentence a helping verb a pronoun