Brainteaser: What is the one thing a queen cannot do that all other pieces can do? A simple brainteaser - A queen cannot do something all other pieces can do. What is that? 

April 18 2014 9:15 PM GMT. EDIT: In this context, by "doing" I mean making a move that leads to the desired result.
I'll have a go at saying the queen is the only piece that cannot reveal a discovered check.