A、Infection. B、Cavity. C、Caries. D、None of the above. A题目问的是男士牙痛可能是什么引起的。选项A为“感染引起的”；选项B为“有洞的”；选项C为“龋齿”。由对话可知，谈话的最后是医生的诊断结果及治疗方案

W: Hello, Mr. Wang. How are you doing?
M: Mm... I’m well, but I have come here for something.
W: Oh, really. Have you been having any problems?
M: (16) I’ve been having a toothache.
W: Can you describe the pain for me?
M: (17) It’s quite a dull pain, and my face is swollen.
W: Is the tooth sensitive to hot or cold?
M: Yes, it hurts when I drink anything hot.
W: Is the tooth tender when you bite on it?
M: Yes, it is.
W: Does it hurt just during the day or at night as well?
M: It hurts all the time...
W: (18) Your tooth is infected, and there might be an abscess under it. (19) I will give you an antibiotic to reduce the infection. If the swelling doesn’ t go down, I’ m afraid I will have to lance it or perhaps root canal. (20) I want you to return in a week, and I will put a gold post in the tooth before I crown it for you, assuming the root canal treatment is successful. We usually have to let the tooth settle for 3 to 6 months before crowning.
16．What is the woman’s occupation?
17．What is NOT true about the man’s toothache?
18．What might be the cause of the toothache?
19．What will the man do about the toothache?
20．When does the woman want the man for a return visit?