【正确答案】 C

【答案解析】[听力原文] M: All smiles this beautiful Monday morning. This morning on Today's Health: how to achieve that glowing smile by changing just a few everyday habits. Liz Vaccariello, the editor in chief in Prevention Magazine, is here to fill us in on some of the surprising effects some foods have on your smile. Good morning. Thanks for being with us today. W: Good morning. M: So the first things first. To achieve that beautiful smile, it's all about daily hygiene, dental hygiene. W: Right! M: Help us out with what we need to know. W: {{U}}There're four things you should do: you should brush twice a day, floss once a day, avoid sugary snacks and see your dentists regularly{{/U}}. (保持牙齿健康应避免甜食，而不是避免咸点心。) He or she will tell you how often that is, but for most of us, that's twice a year. M: It's the flossing that holds a lot of people up. They forget to do it on the daily basis. W: Yes. M: There're some alternative approaches as well that you're going to help us out. We've been joking about the power of cheese, but from what I've read, it's pretty significant. W: Right. {{U}}If you have a big meal, rich in carbohydrates in particular, researchers say a piece of cheese will boost saliva, wash away the acids in the mouth, and the minerals in cheese will help strengthen the tooth from inside out{{/U}}. (奶酪能够帮助分泌唾液，从而冲走腔里的酸性物质，而奶酪里面所含的矿物质也能帮助从内而外坚固牙齿，但并没有提及对整个身体健康的促进作用。) M: Important to know that {{U}}it's not any kind of cheese that will work{{/U}}, (不是所有的奶酪都会对牙齿保健起作用) for example, cheddar. For breast-breed, we're not recommending it. You have lots of news for other people as well. W: Right. M: Drinking out of a straw. Another piece of advice. We've chosen environmentally-friendly straws on these days. W: That's right. All of us want a big Julia Roberts' megawatt smile. People, who are concerned about tooth-staining in particular, use straws to limit the amount of time the liquid, {{U}}which has a deep color{{/U}}, (建议最好用吸管来喝颜色较深的饮料。) is exposed to the tooth. {{U}}But people don't know that often sugary drinks, sodas, even sugar-free sodas have acids that can cause harms to the enamel{{/U}}. (含糖饮料、苏打水甚至无糖的苏打水都含有对牙釉质有害的酸性物质，因此建议用吸管饮用。) M: And {{U}}coffee is well for coffee drinkers in the morning. Is that something you recommend through straws{{/U}}? W: Absolutely. (因为咖啡是颜色较深的饮料，所以建议用吸管来喝。) If you care about oral health and staining in particular. M: {{U}}Perhaps red wine is not going to look as good through a straw, but it could probably work for you as well{{/U}}. (红酒最好用吸管来喝，虽然看起来不太雅观。) W: Not sophisticated. That's right. M: Vitamin C is something we walk away through with the orange juices in the morning. It's good for boosting immune systems. W: Right. Researchers studied this and found that {{U}}people who got less than 60 milligrams a day of Vitamin C had a 25% higher chance of getting gum disease. So you should go for a minimum of 75 milligrams of C a day, upward limit of 2,000 milligrams. So, one orange contains about 80 milligrams{{/U}}. (每天摄取维生素C少于60毫克的人就会增加25%患牙齿疾病的几率。因此每天摄取75至2000毫克的维生素C对保护牙齿都是有益的，而一个橙子所含的维生素C是80毫克。) You may want a supplement. M: Yes. Supplements are going to help you out here as well. So, move along, you're going to talk to us a little bit about calcium, right? Obviously, how many is it for a day? Do you think that 800 milligrams is recommended? W: 800 milligrams? Exactly. 99% of the calcium in our bodies is in our bones and our teeth. And 1,000 milligrams a day is what you should for. If you don't get enough everyday, it can cause severe gum disease. M: And as we look at the soymilk, a lot of people become more and more interested in soymilk and a lot of the health food stores. Is that the same as regular milk in terms of its benefits to you? W: Yes. You should check the label for the amount of calcium. A woman or a man under 50 should get about 1,000 milligrams and 1,200 to 1,500 milligrams if you're over your fifties. M: Okay. There's a lot of concern on dairy products, for example yogurts. If you have the yogurt, you can get a lot of sugar, calcium and other things which could benefit body in the morning. W: That's right. {{U}}There's a lot of power to dairy products when it comes to the mouth{{/U}}. (奶制品，包括牛奶、豆奶及酸奶都可以提供钙质。) M: Speaking of power, the power of tea is critical. Help me out understanding the power of tea. W: Well. {{U}}Both green and black teas contain compounds that prevent plaque from forming. They also contain compounds that prevent bad breath because they address the bacteria{{/U}}. (绿茶和红茶都富含能够阻碍牙菌斑生成及形成口臭的细菌的生长，但没有提及white tea白茶。) M: Tea's good for our health. W: Yes, it is. And in fact, tea, both the leaves and the water contain some substances which can enhance the tooth enamel. M: OK. As we go over, we can see that you also set this out for us as well, say the mushrooms. I think this is the ultimate and alternative approach. W: Right. {{U}}Mushrooms contain compounds that address and eliminate the bacteria in your mouth, which prevent cavities{{/U}}. (蘑菇含有能处理并消除口腔细菌的物质，从而防止龋齿及生牙洞。)You should also take a look at the sugar-free gums that contain something called xylitol, which numerous studies have shown prevents cavities from forming. M: Yes, it's good stuff. Liz Vaccariello, thank you. We appreciate your time today. Thanks for joining US. W: Pleasure.