根据中文提示，把对话中缺少的内容写在线上。这些句子必须符合英语表达习惯。打句号的地方，用陈述句；打问号的地方，用疑问句。

　　提示：Peter给Johnson教授打电话请病假，接电话的是教授的助手Sally。

　　(Peter=P；Sally=S)

P: Hello! This is Peter speaking. 　51　, please?

S: I'm sorry. Professor Johnson is not here at the moment. This is his assistant, Sally.　52　?

P: Yes. Please tell the professor that I'd like to ask for sick leave for tomorrow.

S: Sorry to hear that. May I ask　53　with you?

P: I'm running fever, I've caught a cold.

S: Oh，54　?

P: No, not very serious, but the doctor told me to stay in bed and have a good rest.

S: I see. I'll　55　as soon as he comes back.

P: Thank you. Goodbye!

S: Bye!