A和B分别代表销售员和买书包的人.
A：Welcome to "I love bags" store. How can I help you ?
B：I'd like a schoolbag, because tomorrow is the first day of a new term.
A：Ok. what size do you want, a small one, a middle one or a big one ?
B：A big one please. I have many new subjects this term so a big one is better.
A：And what color of the schoolbag do you want ? We have many colors here.
B：A black one, please.
A：Please wait a minute. Here you are. A big black schoolbag.
B：Thank you very much. I like it. How much is it ?
A：Thirty yuan.
B：Here is the money. Bye bye.
A：Goodbye.
希望帮助到你,满意敬请采纳,O(∩_∩)O谢谢~~