根据上下文的语境，用适当的单词完成句子，每空一词。

  (Rob=R Mom=M)

R: Hi, Mom. I'm back now!

M: Where have you 1_______? It's almost 5:00.

R: Sorry. I was at Sam's house.

M: What 2_______ you doing there?

R: Listening to music. Sam has a lot of great CDs. You should hear some of them.

M: Maybe I'll do that sometime later.

R: How 3_______ now?

M: Now? I'm busy cooking.

R: It doesn't matter. Sam let me borrow some of them. See?

M: Sam let you borrow some of them? 4_______ seems that you borrowed all of them.

R: I only borrowed 15 CDs. Sam has more than 100.

M: Oh, really? The CDs must 5_______ him lots of money.

R: Sure.