Final answer:
The appositive phrase in a sentence provides additional information about a noun, often set off by commas.
Explanation:
In the sentence 'The book, a thrilling mystery, kept me up all night,' the appositive phrase is a thrilling mystery. An appositive is a noun or noun phrase that provides additional information about another noun in the sentence, usually set off by commas.
Learn more about Appositive Phrases here:
https://brainly.com/question/38063455
