听力原文：W: David! Can I give you a hand with one of those grocery bags? M: Sure, Nancy! Could you take this one, please? I didn't realize how heavy these bags would be. W: Why did you buy so much stuff when you have to walk home from the store? M: Well, I didn't intend to buy a lot, but I'm having some people over and I guess I needed more than I expected. W: What's the occasion? M: The people I live with, the Kramers, have been on vacation for a month and I thought I'd surprise them. I'm inviting some of their friends and family for a welcome-home dinner. W: That's really thoughtful of you. M: I figure it's the least I can do for them. They've been letting me stay with them rent-free while I'm in school. W: Really? That's pretty generous of them. M: Well, they understand how difficult it is to make ends meet when you're a student. They've been such a big help to me, I thought that this might be a small way to thank them for their generosity. (20)