10.录音材料：
DIALOUGE
Bear: Hi, Bill and Lily.This is my friend, Elephant.
Bill: Hello, Elephant.
Bear: Where are you going?
Lily: I'm going to the zoo.
Bear: Let's go together.
Bill: Ok!
Bear: The traffic light is green.Let's go!
Bear: Hurry.The light is yellow.
Boy: Hi, Elephant!
Policeman: Why are you stopping here? Go!
Policeman: Go, Elephant!
Bill: I've got an idea!