Question tags, short answers, so do I / neither do I

Question tags check information or ask for agreement. Repeat the auxiliary (or do / does / did) with the pronoun: positive sentence → negative tag, negative sentence → positive tag.

You're Swiss, aren't you? — She doesn't eat meat, does she? — They went home, didn't they? — You can swim, can't you? — He's finished, hasn't he?

Special cases: I'm late, aren't I? — Let's go, shall we? — Open the door, will you? — Nobody called, did they? (nobody is negative).

Short answers: “yes” or “no” alone can sound abrupt. Repeat the auxiliary: “Do you like it?” — “Yes, I do.” / “No, I don't.” “Has she arrived?” — “Yes, she has.” “Can you drive?” — “No, I can't.”

Agreeing: so / neither + auxiliary + subject (inverted):