"That" is just a demonstrative pronoun.
But it's not "Whose car is that car?" The sentence is "Whose car is that?" We don't actually know whether "that" means "that car" or "that one" or "that set of disassembled car parts."
Since "that" could be anything I'm pointing to, it seems to me to be a pronoun and not an adjective (since no object is implied).
While waiting... I don't know if my point in post #9 was clear. We can certainly ask "Whose car is red?" and receive as an answer "Steve's car is red"; we couldn't answer "Red is Steve's car." But if we ask "Whose car is that?" we wouldn't answer "Steve's car is that" but instead "That's Steve's car." For that reason, I think that "that" is not an adjective, and therefore a noun, in the question "Whose car is that?"
The problem with going from "Whose car is that?" to "That car is Steve's" is that it breaks up the phrase "whose/Steve's car." As such it isn't the minimum transformation.
Yes, Einstein and I have just found a link considers "that" as a subject and "whose" as a subject complement but I know that "whose" is a "demonstrative pronoun/adjective" so how could it be a subject complement.This is the paragraph from the previous link which we need:Whose car is that? - That is Steve's car.
The subject in both sentences is "that".
The question word can also be part of a subject complement, as in this example:
A. Whose cup of coffee is this?
B. It's mine.
This question means, 'Who is the owner of this cup of coffee?' The question word 'whose' is part of a subject complement, 'whose cup of coffee'.
'Is' is the verb and 'this' is the subject.
But the link says:
You link does not say that "whose" is the subject complement; it says that "whose" is part of the subject complement "whose cup of coffee."The question word 'whose' is part of a subject complement, 'whose cup of coffee'.
Well, yes, a bit. It makes it much easier to analyze. Because there's only one possible subject ("that car"). "Whose" is an interrogative possessive adjective, and in "that car" "that" is a demonstrative adjective modifying "car." So we would have:If we make a change in the question structure like "whose is that car?" would it make any difference in the analysis?