- 默认语种:
- 播放器快捷键:
-
(F8:播放/暂停 F9:复读)
(F7:播放/暂停 F8:复读)
【科学60秒】氟化物护牙之谜仍未解
听力简介:
Beauty is only ____1____. And the beauty of shiny white teeth is even less deep. Because a new study shows that fluoride forms a thinner protective shield than experts thought it did. The results appear in the surface science journal Langmuir.
American consumers spend more than $50 billion a year fighting cavities. When we realized that fluoride could help, we put it in our drinking water, our ____2____ and our mouthwash. But how does fluoride work its magic? Many figured that fluoride chemically reacts with the main mineral in enamel to form a thick, decay-resistant veneer. But the latest research ____3____ that idea in the teeth.
Scientists in Germany used x-ray photoelectron spectroscopy to get a detailed image of the surface of a treated tooth. And they found that the protective covering is actually only 6 nanometers thick. That’s about a fifteen-thousandth as thick as a sheet of paper. And a layer that skimpy would likely be ____4____ by ordinary chewing.
How fluoride keeps the tooth fairy away is a mystery that researchers are still working to ____5____. In the meantime, we may not know how it works, but we know that it works. So keep brushing.
【视听版科学小组荣誉出品】
请在登录后才能看到内容!
请在登录后才能看到内容!
本文暂未收录注解!
参与沪友(已有48人听写,点击头像查看Ta的听写详情)
听写信息
生词本小D词典
相关网校
注意事项
- 听力练习标点符号不纳入正确率。
- 每天奖励上限为40沪元。
- 无听力原文时提交听写作为参考内容。
- 提交听写后根据正确率来奖励沪元。
- 获取听力mp3下载资源可选择相应下载方式。
- 程序校对,仅供参考,机器做不到人工智能,请大家谅解。