"You've taken my chair."
"It's not your chair."
"You know it's the one I like, and it was in my place."
"How do you know it was in your place?"
"Never mind. I do know."
"No, you don't."
"Yes, I do."
"Suppose I say it was in my place."
"You can't, for it wasn't."
"I can, if I like."