Question tags are the short questions that we put at the end of sentences, especially in spoken English.
• You're coming, aren't you?
• He's not serious, is he?
If the main part of the sentence is affirmative, then the question tag is negative:
• It's warm, isn't it?
• They went also, didn't they?
If the main part of the sentence is negative, then the question tag is affirmative:
• She couldn't see it, could she?
• We won't know till tomorrow, will we?
If the main part of the sentence contains an auxiliary verb (or the verb "to be", then this is used in the question tag:
• They are away for a few days, aren't they?
• You weren't available, were you?
• She's Mexican, isn't she?
• It wasn't his turn, was it?
• You've got a cat, haven't you?
• He's got a new house, hasn't he?
• We can't go in there, can we?
• They couldn't hear me, could they?
If the main part of the sentences does not contain an auxiliary verb, then we use the verb "to do" in the question tag:
• She needs some help, doesn't she?
• He loved his work, didn't he?
• You come here often, don't you?
Depending on what we wish to say, the intonation of a question tag is different. If we are asking a real question (in other words, if we don't know the answer), then our voice rises on the question tag:
• That's spelt with two n's, isn't it?
On the other hand, if we are sure of the answer and are only asking for agreement, our voice falls on the question tag:
• It's your turn next, isn't it?