A、Colleagues. B、Boss-Employee. C、Student-Librarian. D、Lawyer-Client. A人物关系题。从20、21、22各题的选项可以判断，对话与学生的学业有关，因此可以排除B 项。和D 项。对话中女士询问

W: Good morning, Mr. Wang. Can you spare a few minutes?
M: Sure. What can I do for you?
W: I heard you just returned from a lecture tour in the U.S. I was wondering if you’d like to tell me something about campus study there.
M: Yes. Students receive their degrees when they have successfully completed the academic work required by their colleges. To get a B.A. or B.S., a foreign student needs 120 to 132 credits, depending on the field of study.
W: What about an M.A. or M.S. program?
M: The Master of Arts or Master of Science degree usually takes one or two academic years beyond the Bachelor’s degree.
W: What’s the number of credits for the Master’s degree?
M: The minimum number of credits for the Master’s degree with thesis is 24 semester hours, plus 6 hours for completing a thesis. Another type, the Master’s degree without a thesis is 30 semester credit hours. Usually, the student in a nonthesis M.A. or M.S. program is required to pass a comprehensive examination.
W: What’s the focus of graduate study and research?
M: It focuses on a specific field of knowledge. Graduate study is conducted through a variety of means, including lectures, seminars, independent advanced study, special reading courses and participation in research. Research programs leading to Master of arts, Master of Science, or Doctor of Philosophy degrees put special emphasis on the development of the student’s ability for independent scholarly work and the creation of new knowledge through research.
W: Are there any time limits for the completion of degree requirements?
M: Students entering a Master’s degree have fourteen consecutive semesters; students who are granted permission to continue studies towards the doctoral degree after completing an M.A. or M.S. have an additional ten consecutive semesters.
Students working on a doctoral program without a Master’s degree have fourteen consecutive semesters, while those with a Master’s degree have ten consecutive semesters to complete the requirements.
W: I’m really grateful to you for your help, Mr. Wang.
M: My pleasure. If there’s anything I can do to help you in any way, please don’t hesitate to ask me.
W: Thank you.