Statement tags,short answers, clause negation and partial negation

Statement tags

Statement tags function to emphasise what had been already said.

Noun phrase referring back to an earlier pronoun (He helped us a lot, young Mick did. They use some confusing terms, these grammarians.)

Exclamatory comment (He’s won another prize, clever man!)

Colloquially with a verb (That was the week that was.)

Short answers

Short answers are used to make the speech easier, without repeating the same words.

Do you play tennis? Yes, I do. No, I don’t.

Dick plays the violin. So do I.

Dick can’t play the violin. Neither can I. Nor can I. I can’t either.  

Clause negation and partial negation

Clause negation negates the whole verbal action except for the subject. (He's not at home.)

Partial negation negates only one clause element. The verbal action is not negated, only the adverbial or the reason. (Ask John, not his wife. Come early but not before six.)

Instead of employing partial negation (He went there not because of Mary.), language users often shift the negator. Hence the sentence "He didn’t go there because of Mary" may have both the meanings mentioned above. In spoken discourse, the sentence is disambiguated by placing the intonation centre either on Mary (clause negation!) or on didn’t (partial negation).

There is only one negation in Standard English (I can see nobody. I can’t see anybody.). However, dialects like Cockey often employ double negation (I can’t see nobody.)

Since there is only one negator in Standard English, words with negative meaning may render the whole sentence negative: no, nobody, nothing, never, hardly, scarcely, barely, rarely, seldom, little, few. (He can’t do any work. He can hardly do any work.)