A、Teacher and student. B、Patient and doctor. C、Classmates. D、Colleagues. C

W: Hi, Sam, where are you going?
M: I’m going to the Student Union office to find out if Professor Cook has any old exams from years ago.
W: What kind of exams do you want? I took Professor Cook’s class last semester and got an A.
M: Really? But you always work hard. For you, it’s a piece of cake. By the way, do you think that the exams will change from year to year?
W: Yes, but the style is pretty much the same.
M: So tell me about the exam you took. 1 can barely even finish reading the book, let alone remember it.
W: Hey, I am no expert but what Professor Cook will mainly be looking for is that you know the framework of the book, especially the key items.
M: What kinds of questions might he ask?
W: Well, for example, you will probably have to say how the greenhouse effect comes along, and what measures might be taken to reduce the overproduction of carbon dioxide.
M: It seems that I have to go over the book carefully, but time is limited. Did you take notes about it when you took the class?
W: To be frank, I’d like to help you, but the notes I took have already gone missing.
M: Are you kidding me? Now you are the only person to save me. If you do me a favor, I will treat you to a big dinner. Moreover, there is a vocal concert ticket for you.
W: It sounds beautiful. I have to help you with the exam? OK, see you in the library.
M: That’s kind of you! See you then.