听力原文：M: Hi, Sara. What's up? W: Oh, hi, I just got out a history class. I had to give a presentation. M: How did it go? W: Terribly. I'm sure I made a fool of myself. M: Why? Weren't you prepared? W: No, it was not that. I just get so embarrassed and nervous wherever I have to speak in front of a group of people. I stand up and my face gets red and then I get even more nervous because I know everyone can see me blushing. M: It's not so bad to blush. W: But it happens all the time. If the professor asks a question and I know the answer, I blush like crazy if he calls on me. Doesn't that ever happen to you? M: No, not really. Maybe you should just try to forget the people. Look at something else in the room like the exit sign. W: I guess I could try that but I doubt if it'll help. M: You know we talked about it in psychological class. Blushing, even though it's involuntary, is more or less a learned behavior. W: What do you mean? M: Oh, children hardly ever blush at all. And among adults, supposedly, women blush more than men. W: I wonder why? M: I don't know, but I have a friend at high school, Brian Smith. It was really easy to make him blush. He turned red whenever a waitress would ask him for his order. W: I'm not that bad. Well, I've got to get going for my next class. I'll talk to you later. Q. 19. What was the woman's problem? Q. 20.Why might looking at the exit sign help the woman? Q. 21.What does the man say about children? Q. 22.Why does the man mention his friend Brian? (39)