听力原文：M: Hi, Janet. Where were you at lunchtime？ I was saving a seat for you in the cafeteria.
W: Oh! Sorry to miss you. But my thirst for knowledge was greater than my pains of hunger!
M: I've never had that problem. So where were you？
W: My political science class ran overtime(24) . That's been happening quite a bit lately, hasn't it(24) ？
W: I guess so. Actually what happens is that a bunch of us hang around for a while after class to talk with our professor and ask him questions(23) .
M: Who is this twentieth century Socrates？
W: Professor Hall. Have you heard of him？
M: Hm, he does have a good reputation in the Political Science Department.
W: And a well-deserved one! The same students who fall asleep in discussion groups and seminars fight for front-row seats in his lectures(25) .
M: Oh, no! I hope this isn't catching!
W: You can joke. But it's great to have a professor who's not only interesting, but also prepared to give up time for students.
M: I know. They're a rare sort. Maybe I should sit in on his class sometime. Do you think he'd care？
W: Not at all. Lots of students bring their friends, and he says he feels pleased.
M: Well, just to be safe, I think I'll bring my lunch along as well.
W: I'll make a good student of you yet.
(20)

A. Giving a lecture.
B. Discussing political science.
C. Working on a science problem.
D. Reading twentieth-century literature.