Tag Questions

Tag questions are questions that are added at the end of a sentence.
--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.
 

FIRST PART OF SENTENCE:	TAG QUESTION:
affirmative	negative
negative	affirmative

In American English, a form of do is usually used when have is the main verb: They have change, don't they?