Tag questions are
questions that are added at the end of
--Mary is here, isn't she?
--You like beer, don't you?
--They are leaving, aren't they?
--She doesn't drink coffee, does she?
--He has brown hair, doesn't he?
The subject of the tag question should
be the same as the subject of the main
verb. If the first part of the sentence
is in the affirmative, then the tag question
will be negative, and vice versa.
In American English,
a form of do is usually used when
have is the main verb: They
have change, don't they?