Who are the speakers?

M: Polly, Ms. Kelly has agreed to come and give a talk about international relations next week. When do you think we can fit her lecture in?
W: That’s great, Nick. What about Friday afternoon, then?
M: I’ m afraid some students are planning to go on a trip. Maybe we can have it on Wednesday afternoon.
W: No, that’ s not possible either. Most students are having group activities for their research projects. Well, I have an idea. I have a class on Tuesday afternoon, and probably Ms. Kelly can use my time.
M: That’ s possible. But I have to speak to Dr. Li about that, and you should also talk to the students about the change.
W: Oh, yes. I’ll certainly do that.