What are the rules for using question tags in tag questions?

The rules for using question tags in tag questions are as follows:

1. The question tag is formed by using an auxiliary verb that matches the tense of the main clause. For example, if the main clause is in the present tense, the question tag will use the auxiliary verb "do" or "does" for singular subjects and "don't" or "doesn't" for plural subjects.

2. If the main clause is in the past tense, the question tag will use the auxiliary verb "did" for both singular and plural subjects.

3. The subject of the main clause is usually replaced by a pronoun in the question tag. For example, if the main clause is "You are going, aren't you?" the pronoun "you" is replaced by "aren't you" in the question tag.

4. If the main clause is positive, the question tag is usually negative, and vice versa. For example, if the main clause is "She is coming, isn't she?" the positive statement "is coming" is followed by the negative question tag "isn't she?"

5. If the main clause contains a negative word or phrase, the question tag is usually positive. For example, if the main clause is "Nobody knows, do they?" the negative word "nobody" is followed by the positive question tag "do they?"

6. In imperative sentences, the question tag is usually "will you?" For example, "Open the window, will you?"

These are the general rules for using question tags in tag questions.