Question tags are grammatical elements that are placed at the end of a sentence in the form of a short question and whose structure is opposed to the previous sentence. That is, if a sentence is affirmative, the question tag that accompanies it will be negative, and vice versa. For example, in: Your son is growing up so fast, isn't he? (Your child is growing very fast, right?) The first sentence states that the child is growing very fast, while the final question is expressed in a negative way.