A question tag

   A question tag (also known as question tail) is a grammatical  structure in which a declarativetor an imperative statement is turned into an interrogative fragment Questions. As a part of grammar, a question on (Add a question tag) is usually asked in the examination.

We add question tags to the end of statements to turn them into questions. They are used in spoken language, especially when we want to check something is true, or invite people to agree with us. We add a clause in the form of a question at the end of a sentence.

A tag question is a small question that is attached , or "tagged", to the end of a sentence. Rather than repeat the main verb, a form of "be" or other auxiliary verb or modal is used in the tag. Below are a few examples.

You came by train, didn’t you?
It’s very windy today, isn’t it?
You can meet me at the station, can’t you?
You couldn’t give me a ride, could you?

Sentence Pattern

If the sentence is negative, the tag is usually positive, as in the example below.

You didn’t tell him, did you?

Note: Sentences with negative words are considered to be negative. Therefore, they require positive tag question endings, as in these examples:

He never drinks alcohol, does he?
Nobody left a message, did they?

If the sentence is positive, the tag is usually negative, as in the next example.

You told him, didn’t you?

Twelve Rules for Tag Questions

1. After “let’s”, the tag begins with “shall”.
Let’s invite the neighbours over for dinner on the weekend, shall we?

2. Use “aren’t I” in tags to mean “I am not”.
I’m on time, aren’t I? (correct)
I’m on time, am’t I? (incorrect)

3. Use “won’t” for polite request tags.
You’ll bring the other things, won’t you?
Use “will” or “would” with imperative sentences (commands).
Wait here until I return, will you?
Wait here until I return, would you?

5. Use “mustn’t” with the modal “must”.
This must be the address, mustn’t it?

6. Two endings are possible when “have” is the main verb of the sentence.
You have enough money, haven’t you? (British English)
You have enough money, don’t you? (North American English)

7. Use pronouns for people, not proper names, in question tags.
Paul is a good tennis player, isn’t he?
Betty has a good job, hasn’t she? 

8. Use “it” in a question tag when the sentence includes the words “this” or “that”.
This is your pen, isn’t it?

9. Use “they” in a question tag when the sentence includes “these” or “those”.
Those are your sandals, aren’t they?

10.Use “there” in a question tag when the sentences includes “there + a form of be”.
There is a lot of work to do today, isn’t there?

11. Use “they” in a question tag when the sentence includes indefinite pronouns
(nobody, no one, someone, somebody, everyone, everybody).
Everyone is here now, aren’t they?
Nobody has eaten yet, have they?

12. Use “didn’t” in a question tag when the sentence includes the verb “used to”.
You used to go skating very often, didn’t you?