A practical english grammar - Vyssaja skola 1978
Tag questions
Sound symbols
The tag question, sometimes called “attached question,” is a short question attached to a statement in English to ask confirmation of it or agreement with it—the equivalent of “n’est-ce pas?” in French, “^no es verdad?” in Spanish, “nicht wahr?” in German. There is an essential difference, however, between English and those other languages. In French, Spanish, and German the tag question has only one form, regardless of the sentence that precedes it; this is not so in English.
The tag question in English is formed according to the following rules.
1) Only auxiliary verbs or be appear in tag questions. If the main sentence has an auxiliary, then the tag question uses the same auxiliary. If the main sentence does not have an auxiliary, then the tag question contains do, does, did, or a form of be.
2) If the subject of the main sentence is a pronoun, the word one or the dummy it or there, the tag question has the same subject; if the subject of the main sentence is a noun or noun construction, the subject of the tag question is the pronoun that replaces that subject.
3) If the main sentence is negative, the tag question must not contain n’t or not; if the main sentence is not negative, the tag question must include n’t or not.
Study these examples:
Those boys are students, aren’t they?
You’re his father, aren’t you?
You like ice cream, don’t you?
You and I have finished, haven’t we?
They arrived yesterday, didn’t they?
You haven’t lost your sweater, have you?
They hadn’t already left, had they?
One never knows what to expect, does one?
There aren’t any strawberries, are there?
The tag question is spoken with a rising intonation if the speaker is rather uncertain and is asking for confirmation of what he has said. The tag question is spoken with a falling intonation if the speaker is certain and is asking for agreement with what he has said.
