This pattern is used with be, do, and have to form question tags, which ask the hearer or reader to confirm a statement. A negative statement is always followed by a positive question tag. A positive statement may be followed by a negative or a positive question tag. A negative question tag following a positive statement indicates that the information is considered to be shared. A positive question tag following a positive statement indicates that the information is not considered to be shared, but is something that the hearer alone has the right to confirm or deny.
cl AUX nThe auxiliary verb follows a clause and is followed by a noun group. The noun group is the Subject of the auxiliary verb. It is usually a personal pronoun.
|clause||Auxiliary verb||noun group|
|She isn't laughing,||is||she?|
|You live in Birmingham,||don't||you?|
|They hadn't been arrested,||had||they?|
In the case of be and have, the clause contains a verb formed with be or have as an auxiliary. In the case of do, the clause contains a verb formed with do as an auxiliary, or a verb formed without an auxiliary.
Ah, you're making an assumption there, are you?
He isn't wearing shorts, is he?
You liked Gil, didn't you?
They'd moved up here before you were born, had they?