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.

党的十八届六中全会通过的《关于新形势下党内政治生活的若干准则》提出，各级领导干部必须（），多到条件艰苦、情况复杂、矛盾突出的地方解决问题，千方百计为群众排忧解难。

A.深入实际

B.深入基层

C.深入群众

D.深入一线