[justinwschang]

Originally Posted by Soup

So, you're saying next is an adverb because it tells us where the person is, right? So,

Location = adverb
Who is upstairs in the house?
Who is in the house upstairs?
However, often when the word order changes, the part of speech changes or the meaning changes:
The above picture is of Darth Vader (adjective)
The picture above is of Darth Vader (adverb)
He painted the red door (adjective)
The painted the door red (noun)

Who is next in line?
Who is in line next?

Cool.

Adjective: Who is (the) next (person in line)?
Adverb: Who is (the person) next (in line)?