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.
