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The use of fluoride to protect teeth is common in many parts of the world. For example, it is often added to drinking water supplies. The fluoride mixes with enamel, the hard surface on teeth, to help prevent holes, or cavities, from forming.
在全球很多地区都通常使用氟化物保护牙齿。例如，它常常被添加到饮用水中。氟化物和牙釉质混合的坚固表面可以防止蛀牙的形成。
But young children often swallow toothpaste when they brush. The American Academy of Pediatric Dentistry notes that swallowing fluoridated toothpaste can cause problems. So young children should be carefully supervised when they brush their teeth. And only a small amount of fluoridated toothpaste, the size of a pea, should be used.
幼童刷牙时常会吞下去牙膏，美国儿童牙科学会称，吞咽含氟牙膏会有问题，所以幼童刷牙时要有大人严密监督，幼童只能使用很少量的含氟牙膏，豌豆粒那么大小即可。
When baby teeth begin to appear,you can clearly what to brush ,dentist say it is important to find soft tooth brush,maybe for baby,and use them very gently.
When I'm a little girl about eight years old ,I usually swallow toothpaste,becase I think it's very delicious, I wondered what effect swallowing toothpaste might have on my body when I grew up,but as a result I'm very healthy till now.
发表于 2012-1-18 15:46
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发表于 2012-4-23 12:08
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高二了，才来练听力会不会太晚啊？听不懂怎么办？？？？？？？？