When it's all rusty, right? Originally, "moldy".

All right, here's a question: When is a pan a pan, yet you can't use it on the stove? Originally, "When is a pan (bread) a pan, yet you can't eat it?" "When it's a frying pan."

But that's the right answer. Everything Hakurei Reimu says is the right answer!

Things like that are why you're called a fool.

I don't really get it, but if I beat her, that'll solve everything?