Final answer:
The underlined word in the sentence is an adverb.
Step-by-step explanation:
The underlined word in the sentence is an adverb.
An adverb is a part of speech that modifies or describes a verb, an adjective, or another adverb. In the given sentence, the word 'then' is modifying the verb 'I'll get a raise.' It indicates the time frame for when the speaker expects to receive a raise.
Other examples of adverbs include 'quickly,' 'slowly,' 'happily,' and 'carefully.'
Learn more about Parts of speech