Question tags are basically short questions which appear at the end of the sentences. When it comes to day to day speech or any kind of informal writing the use of question tags is very common. But the use of these tags is very uncommon in case of formal writing. Some of the examples of question tags are as follows:
It is very hot, isn’t it?
She sings well, doesn’t she? Or if you want to put in another way you can say, She sings well, doesn’t she?
Generally the trend is that in case of informal sentences the negative form is written in short which means instead of writing is not it we tend to write isn’t it. But this style of contraction can be used only in case of informal writings but in case of formal writings we should use the full form like, They said they would finish the work in six months, did they not?
If we had to write this same sentence in an informal tone we would have written it in the form: They said they would finish the work in six months, didn’t they?
The main purpose of using question tags is to find whether something which is said is true or not. The tags are also used to get some kind of agreement against the statement or in favor of the sentence.
The thumb rule of the use of question tags is that you use negation after an affirmative sentence and vice versa. And at the same time please remember that question tags are always used in case of negative and affirmative sentences and they are not used after questions.
It can be explained in a better manner with the help of the examples”
You are the new Chairman, aren’t you? (A correct usage)
You aren’t the new Chairman, are you? (A correct usage)
Are you the new Chairman, aren’t you? (An incorrect usage)
In case of affirmative sentences we are supposed to use negative tags.
She is a good girl, isn’t she? (And not “is she”)
It isn’t hot today, is it? (And not “isn’t it”)
Another rule which you need to keep in mind is that if the main sentence has an auxiliary verb you are supposed to use the auxiliary in the question tag also.
Some of the examples are:
They are busy, aren’t they?
She is going, isn’t she?
They haven’t arrived, have they?
On the other hand if the main sentence does not have an auxiliary verb in that case the tag takes the various forms of the verb “do”.
You love fish, don’t you?
She came today, didn’t she?
Finally it can be concluded saying that question tags are phrases which are added to the main part of the sentence. These tags generally invite opinion from the listener. But the most important thing in these tags is that affirmative is followed by negative and vice versa. As you use the tag the verb always comes in front of the noun or the pronoun.