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Phrase(s): What does that prove?
Fig. So what?; that does not mean anything. (A defensive expression. The heaviest stress is on that. Often with so, as in the examples.) • Tom: It seems that you were in the apartment the same night that it was robbed. Bob: So, what does that prove? Tom: Nothing, really. It’s just something we need to keep in mind. • Rachel: You’re late again on your car payment. Jane: What does that prove? Rachel: Simply that you can’t afford the car and we are going to repossess it.
McGrawhill's American Idioms And Phrasal Verbs