Why can’t the woman get the size she wants?

W: Could I see a pair of leather shoes like the white ones in the window? I need a size twenty five and a half.
M: I’m sorry but that style doesn’t come in half sizes. Can I show you a twenty six?

M: Hi, Jane. Where are you going?
W: Oh, hi, Bob. I’m on my way to the library.
M: I just wondered if you wanted to go to a concert with me.
W: I’d love to, but I can’t. I can’t relieve all the work I have today.