A、Have one’s heart transplanted. B、Have one’s teeth transplanted. C、Advance the tooth filling technique. D、Reduce pain in tooth

M: Mary. I heard that you are suffering from toothache these days. How’s that with you now?
W: It’s gone, thanks. I went to the dentist last night, and he took care of me.
M: What exactly is troubling you then?
W: The last tooth on the upper right hand side. It’s been severely decayed and finally I had it filled at the dentist’s.
M: I hate having my teeth filled. It’s not just the pain I hate. I also hate the sound of drilling.
W: So do I. I’d rather have a tooth pulled than filled.
M: Have you ever had one of your teeth pulled?
W: No, but the one the dentist just filled will have to come out someday. He says it can’t be filled again.
M: Teeth keep causing trouble, and nobody really does anything about it. I can’t understand why.
W: They can put men onto the moon, but they can’t keep people from having trouble with teeth.
M: They can give somebody a different heart. Why can’t they give him different teeth?
W: I’ve heard they’re working on that. My dentist says they’re working on tooth transplant right now.
M: But on second thought, I’m not sure I’d want to eat with some other person’s teeth.
W: Well, that’s not how it works. The idea is to develop a plastic tooth that can be placed into the hole where your own tooth came out.
M: Really? It sounds like a good idea.
19. Why did the woman go to the dentist?
20. What does the man hope the dentists can do?
21. What does the woman’s dentist tell her?