【正确答案】 A

【答案解析】[听力原文]
M: Now all the tartar is gone; your teeth are clean. I"d like you to come in again in six months. Between now and then, you need to make an effort to keep your teeth clean.
W: What should I do?
M: There are several things to do. First of all, be sure to brush your teeth at least twice a day, and floss your teeth every day. There are some other devices on the market that may help you; we"ll talk about those later. The basic things to do are brushing and flossing.
W: I"m not sure how to do that. I"ve never flossed my teeth before.
M: Well, dental floss is a thin string. You can buy it at any drug store. I"ll give you a sample when you leave. With the floss, you can drag the tartar from between your teeth at the gum line.
W: But what"s tartar?
M: Tartar is the white gummy stuff that stays between your teeth on the gum line after eating. It"s composed of bacteria, and that"s what makes our teeth decay.
W: Oh, I guess I"d better start flossing right away.
M: Yes. Flossing helps keep your teeth clean because it helps prevent the build-up of tartar.
W: OK. Can you show me again how to use it?
M: Sure. Take a piece of floss about this long and hold it like this in two hands. Here"s a mirror. Now open your mouth again and watch me as I pull it between your teeth.

When should the patient come to see the dentist again?

[解析] 题目问病人什么时候再来看牙医。原文中医生说希望病人六个月后再来。故答案为A。

【正确答案】 C

【答案解析】[听力原文]
What does the dentist say the woman should do to keep her teeth healthy?

[解析] 题目问医生告诉女士应该如何保护牙齿。在病人问医生该怎么办的时候，医生回答道首先每天刷两次牙；其次每天用牙线剔净牙缝。故C是正确答案。

【正确答案】 A

【答案解析】[听力原文]
According to the dentist, why is tartar a problem?

[解析] 题目问医生为什么觉得牙垢是个大问题。医生说牙垢是白色黏性的东西，它由细菌构成，会使我们的牙齿被腐蚀。故选项A“牙垢会导致腐蚀”为正确答案。

【正确答案】 D

【答案解析】[听力原文]
What is the importance of dental floss?

[解析] 题目问牙线的重要性。原文中医生提到它防止牙垢的聚积，故D“使牙垢分散”为正确答案。

【正确答案】 A

【答案解析】[听力原文]
What is the dentist probably going to do next?

[解析] 题目问牙科医生接着要做什么。原文中医生最后正在边说边演示，他把牙线拉到了病人齿间，下一步可能让女的模仿自己的做法，故答案为A选项“教女士用牙线”。