情景对话。
A How much is it?
B a bookbag
C which one?
D Can I help you?
E Here's the money.
（1）W:        
（2）H: Yes. I want     please.
（3）W:    This one?
H : No , not that one. The red one.
W: This one?
（4）H : Yes.         
W : It's forty yuan.
（5）H:     Thanks a lot.