A、Reading the instruction. B、Observing two pictures. C、Discussing a girl’s looking. D、Doing some math problems. B女士说两幅画有20处不同，她已

W: I made a big mistake today. I read a student’s article to the class and pointed his errors out. I meant the whole class to learn from his article. Then I saw he was lowering his head and I realized he was hurt.
M: It is the teacher’s responsibility to point out students’ errors but not in public. For some of the students have a strong sense of self-respect.
Q: What are they mainly talking about?

W: The instruction says there are altogether 20 differences between these two pictures. I can only figure out 19. Come over and help me find the last one. It is really hard for me.
M: You look at the angle of the girl’s head. In the left picture, the tip of her nose can be seen.
Q: What are the two speakers doing?