Tag questions (or: question tags) are a grammatical structure in which a declarative statement or an imperative is turned into a question by adding an interrogative fragment (the "tag").
They can be an indicator of politeness, emphasis, or irony. They may suggest confidence or lack of confidence; they may be confrontational or tentative. Some examples showing the wide variety of structure possible in English are:
Open the window, will you?
She doesn't really want that, does she?
You'd better stop now, hadn't you?
So you thought it would be a good idea to reprogram the computer, did you?
It's quite an achievement, isn't it, to win a Nobel prize!
Oh I must, must I?
I just adore Beethoven, don't you?
I'm coming with you, all right?
Easier said than done, eh?
You went there, no?
The English tag question is made up of an auxiliary verb and a pronoun. The auxiliary has to agree with the tense, aspect and modality of the verb in the preceding sentence. If the verb was in the perfect tense, for example, the tag question uses has or have; if the verb was in a present progressive form, the tag is formed with am, are, is; and if the sentence has a modal verb, this is echoed in the tag:
He's read this book, hasn't he?
He read this book, didn't he?
He's reading this book, isn't he?
He reads a lot of books, doesn't he?
He'll read this book, won't he?
He should read this book, shouldn't he?
He can read this book, can't he?
English tag questions may contain a negation, but need not. When there is no special emphasis, the rule of thumb often applies that a positive sentence has a negative tag and vice versa:
She is French, isn't she?
She's not French, is she?
These are sometimes called "balanced tag questions". However, it has been estimated that in normal conversation, as many as 40% of tags break this rule. "Unbalanced tag questions" (positive to positive or negative to negative) may be used for ironic or confrontational effects:
Do listen, will you?
Oh, I'm lazy, am I?
Jack: I refuse to spend Sunday at your mother's house! Jill: Oh you do, do you? We'll see about that!
Jack: I just won't go back! Jill: Oh you won't, won't you?
Patterns of negation can show regional variations. In North East Scotland, for example, positive to positive is used when no special effect is desired:
This pizza's fine, is it? (standard English: This pizza's delicious, isn't it?)
Note the following variations in the negation when the auxiliary is the I form of the copula:
England: Clever, aren't I?
Scotland/Northern Ireland: Clever, amn't I?
nonstandard dialects: Clever, ain't I?
English tags can have a rising or a falling intonation pattern. We may contrast this with French or German, for example, where all tags rise. As a rule, the English rising pattern is used when soliciting information or motivating an action, that is, when some sort of response is required. Since normal English yes/no questions have rising patterns (e.g. Are you coming?), these tags make a grammatical statement into a real question:
You're coming, aren't you?
Do listen, will you?
Let's have a beer, shall we?
The falling pattern is used to underline a statement. The statement itself ends with a falling pattern, and the tag sounds like an echo, strengthening the pattern. Most English tag questions have this falling pattern.
He doesn't know what he's doing, does he?
This is really boring, isn't it?
Sometimes the rising tag goes with the positive to positive pattern to create a confrontational effect:
He was the best in the class, was he? (rising: the speaker is challenging this thesis, or perhaps expressing surprised interest)
He was the best in the class, wasn't he? (falling: the speaker holds this opinion)
Be careful, will you? (rising: expresses irritation)
Take care, won't you? (falling: expresses concern)
Sometimes the same words may have different patterns depending on the situation or implication.
You don't remember my name, do you? (rising: expresses surprise)
You don't remember my name, do you? (falling: expresses amusement or resignation)
Your name's Mary, isn't it? (rising: expresses uncertainty)
Your name's Mary, isn't it? (falling: expresses confidence)
It is interesting that as an all-purpose tag the London set-phrase innit (for "isn't it") is only used with falling patterns:
He doesn't know what he's doing, innit?
He was the best in the class, innit?
On the other hand, the adverbial tag questions (alright? OK? etc.) are always found with rising patterns.
English tag questions are normally stressed on the verb, but the stress is on the pronoun if there is a change of person.
I don't like peas, do you?
I like peas, don't you?
This is often a rising tag (especially when the tag contains no negation), or the intonation pattern may be the typically English fall-rise. In French, this would be expressed with et toi?, which is also a kind of tag question.
Is it clear?