These are shortened questions.
Look at this sentence.
You are coming tomorrow, aren't you?
In this sentence the speaker has said something and then added a short question. He expects the listener to say yes and seeks confirmation.
This short question is called a question tag.
Question tags are very common in conversations.
Rules of Question Tags
1. The verb in the question tag is either the auxiliary used in the statement or the proper form of do, does, did.
2. If the statement is affirmative, the question tag should be negative.
This negative is formed by combining the auxiliary with 'n't'. But the statement is negative, the question tags will be positive.
E.g.
He is not very intelligent, is he?
He is very intelligent, isn't he?
3. There is always a comma between the statement and the question tag. And a question mark at the end of the sentence.
4. Sentence and question tag must be in the same tense.
5. Always use pronoun in question tag.
6. Always use contracted form in negative question tag.
Examples
(a)Positive statement takes negative question tag
1. I am in time, aren't I?
2. He is naughty, isn't he?
3. It is noisy class, isn't it?
4. They are reaching tomorrow aren't they?
5. The hotel rooms were dirty, weren't they?
6. You have finished writing, haven't they?
7. She had typed all the letters, hadn't she?
8. It had stopped raining, hadn't it?
9. She has a new dress, hasn't she?
10. Smith lives here, doesn't he?
11. They speak English at home, don't they?
12. You ate a lot, didn't you?
13. You settle this yourself, can't you?
14. You could help me, couldn't you?
15. You will stay with us, won't you?
16. They will join us at the picnic, wouldn't you?
17. We shall reach there by tomorrow, shan't we?
18. I should send this letter today, shouldn't I?
19. We must give more time to Arabic, mustn't we?
20. You must buy the tickets in advance, mustn't you
21. We ought to work for country, oughtn't we?
22. We used to live here, didn't we?
NEGATIVE STATEMENTS TAKE POSITIVE QUESTION TAGS.
1. I am not at fault, am I?
2. The book isn't very interesting, is it?
3. They aren't very tactful, are they?
4. The women at the party weren't quiet, were they?
5. There weren't many people at the function, were they?
6. You haven't any books on painting, have you?
7. They haven't any trains in Arabia, have they?
8. Smith hasn't much commonsense, has he?
9. The car hadn't much petrol, had it?
10. He doesn't understand French, does he?
11. They didn't play well, did they?
12. She doesn't love you, does she?
13. You don't want to marry that fat girl, fo you?
14. We can't go on living like this, can we?
15. They can't always fool us, can they?
16. The mountaineers couldn't climb the peak, could they?
17. You couldn't possibly believe him, could you?
18. They may not leave without permission, may they?
19. You mustn't delay marriage, must you?
20. You needn't be in such a hurry, need you?
21. He oughtn't to betray his friend, ought he?
22. We shan't go with them, shall we?
23. She shouldn't drive so fast, should she?
24. The bird won't fly away, will it?
25. They wouldn't lose their way in the city, would they?