【正确答案】 A

【答案解析】[听力原文] 18-21
M:How's your toothache?
W:It's gone, thanks. I went to the dentist last night, and he took care of it.
M:Which tooth was it?
W:The last one on the upper right hand side. It has a huge filling now.
M:I hate having my teeth filled. It's not just the pain I hate. I 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 on the moon, but they can't keep people from having trouble with teeth.
M:Why can't they transplant teeth the way they transplant hearts? 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 transplants right now.
M:On second thought, rm 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 put into the hole where your own tooth came out.
M:Really? What makes it stay there?
W:So far they haven't tried it with people, but they've made it work with baboons.
M:Do they hook the plastic tooth to the teeth beside it?
W:No.The plastic tooth is made with plastic roots, and after a while the gums grow around the roots, so the tooth can't fall out.
M:Well, it sounds like a good idea.