英语电话对话（A Telephone Call）
Mary是个学生，因患感冒第二天不能到校上课，于是打电话给她的老师Green先生请假。恰巧Green先生外出，John接了电话。John答应等Green先生回来后将情况转告他。
要求：
请根据上面提示，编写一段80至100字的电话对话。

A Telephone Call
John: Hello.
Mary: Hello. May I speak to Mr. Green, please?
John: Sorry, but he's not in right now. Who's calling, please?
Mary: This is Mary, his student.
John: Hi, Mary. Can I take a message?
Mary: Oh, yes. Please tell him I've got a bad cold and the doctor told me to stay in bed for one or two days. So I won't be able to attend the class tomorrow.
John: O. K. I'll give him the message when he comes back.
Mary: Thank you. Good-bye.
John: good-bye.