We usually use Question Tags to ask a question when we think we know the answer (or want the answer to be something in particular) and are asking for confirmation. Our intonation (voice; pitch) goes up at the end if we are hesitant or uncertain, but if we are more confident, our intonation goes down at the end, like it would for declarative sentences.
The three parts to Question Tags are these:
- repeat the same AUXILIARY VERB from the original clause; with multiple, repeat the first; with none, use a form of 'do'
- balance the positives and negatives
- finish with a PRONOUN that matches the subject.
An alternate form of Question Tags involves rhetorical questions, which might be expressing irony or imperatives (asking someone to do something). In these cases, do not balance the positives and negatives.
There should be a comma between the first clause and the tag, and the sentence should end with a question mark (although some imperative rhetorical questions can end with an exclamation mark).
Watch this video for details: www.youtube.com/watch?v=H1r3lfcsRx4
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