你对牙齿了解多少

Everybody has teeth . We all know that teeth help us eat. But is that all about teeth? How much do you know about teeth?
It is very
important to brush your teeth every day, otherwise such cavities will grow on your teeth. Cavities are holes that grow in your teeth. If
you do not brush your teeth often, there will be some small food residues left in the gaps between the teeth after eating. Bacteria use these residues as food, and they will increase . Bacteria will produce something called “acid ”, which can corrode hard things. Therefore, the food remaining on the teeth will help the bacteria to grow continuously , the hard teeth will be corroded little by little , and the teeth will form small holes, which are cavities. A tooth with a hole is a tooth decay.
1. Why do you need to brush your teeth every day? Why is there tooth decay?
每个人都有牙齿。

我们都知道牙齿帮助我们吃东西。

但是，这就是牙齿的全部吗？你对牙齿又了解多少呢？
为什么需要每天刷牙？为什么会有蛀牙？
你对牙齿了解多少？
广东中山市卓雅外国语学校 刘杰琳 编译
How Much Do You Know about Teeth?
There are different types of teeth in our mouth. The front teeth are called front teeth, and the teeth next to the front teeth are pointed, called fangs . Look at the teeth at the back. They are molars . Put the food in the mouth, the front teeth like a chisel will cut off the food; the sharp teeth like an awl will help tear the food apart ; the molars like a stone mortar will grind
the food so that when the food enters the stomach , we can get it nutrition .
2. How do teeth work?
每天刷牙是非常重要的，否则牙齿上就会长出这样的龋洞。

龋洞，就是牙齿里长出来的洞。

如果经常不刷牙，吃东西以后，会有一些细小的食物残渣留在牙齿缝里。

细菌拿这些残渣当食物，就会繁殖得越来越多了。

细菌会制造一种叫“酸”的东西，它能腐蚀
坚硬的东西。

所以残留在牙齿上的食物就会帮助细菌不断生长，坚硬的牙齿就会一点一点地被腐蚀，牙齿就会形成一个一个小洞洞，这就是龋洞。

有了洞洞的牙齿，就是蛀牙。

我们嘴巴里有各种不同类型的牙齿，最前面的牙齿叫作门牙，门牙旁边的牙齿是尖的，叫作尖牙。

看看那些位置靠后的牙齿，它们是磨牙。

把食物放进嘴里，像凿子一样的门牙会把食物切断；像锥子一样的尖牙会帮忙撕开
牙齿怎么工作？
We generally start to grow deciduous teeth from 6 months old, and we have 20 deciduous teeth when we grow to about 2 and a half years old. At the age of six or seven, they will fall one by one, and new permanent teeth will grow. Adults will have 28-32 permanent teeth. Everyone has only one chance to change permanent teeth.
Brush your teeth! To remove the food residue left between the teeth, you need to brush your teeth. Also, don’t eat too many sweets. In this way, we will have healthy teeth!
3. How many teeth do we have?
4. How to protect teeth?
食物；像石臼一样的磨牙会把食物磨碎，这样食物进入肚子后，我们就可以得到营养。

我们有几颗牙齿？
怎么保护牙齿？
我们一般从6个月开始长乳牙，长
到2岁半左右共有20颗乳牙。

在六七
岁时乳牙会一颗一颗掉落，再长出新的
恒牙。

成年人有28～32颗恒牙。

每个
人都只有一次换恒牙的机会。

刷牙！要把留在牙缝里的食物残渣清除干净，就需要刷牙。

另外，不要
吃太多的甜食。

这样，我们就会有健康的牙齿啦！
teeth n . （tooth 的复数）牙齿tooth decay 蛀牙important adj .重要的 otherwise adv . 除非 cavity n .龋洞hole n .洞；空腔food residue 食物残渣 gap n .缝隙bacteria n .细菌increase v .增长；增加acid n .酸 corrode v .侵蚀hard adj .硬的remain v . 保留
continuously adv . 不断地little by little 一点一点地form v . 形成type n . 类型
Notes:
fang n . 尖牙molar n . 磨牙chisel n .凿子 sharp adj . 锋利的 awl n .锥子
tear … apart 把……撕开stone mortar 石臼 grind v .磨
stomach n .胃；肚子nutrition n .营养generally adv .一般地 deciduous teeth 乳牙permanent teeth 恒牙adult n. 成年人protect v . 保护remove v . 移动in this way 这样healthy adj . 健康的。