职务名称英文:英语课上的问题 帮我答出来我给30分！！

1.Toothpaste was used as long ago as 500 BC in both China and India; however, modern toothpastes were developed in the 1800s. In 1824, a dentist named Peabody was the first person to add soap to toothpaste. John Harris first added chalk as an ingredient to toothpaste in the 1850s. In 1873, Colgate mass-produced the first toothpaste in a jar. In 1892, Dr. Washington Sheffield of Connecticut manufactured toothpaste into a collapsible tube. Sheffield's toothpaste was called Dr. Sheffield's Creme Dentifrice. In 1896, Colgate Dental Cream was packaged in collapsible tubes imitating Sheffield. Advancements in synthetic detergents made after WW II allowed for the replacement of the soap used in toothpaste with emulsifying agents such as Sodium Lauryl Sulphate and Sodium Ricinoleate. A few years later, Colgate started to add fluoride to toothpaste.
2. 32 for the adult
3. bacteria readily metabolize various amino acids from foods, salivary peptides and proteins in oral cavity, and release gases as by-products -- a process called bacterial putrefaction.
4.Black tea is good for teeth

1.人类在没有牙膏之前用树叶,也正是因为人咀嚼树叶后来便发明了牙膏
2.一般都是32颗
3.因为每天吃饭有食物渣滓残留在牙缝间,所以会产生细菌
4.淡茶水会对牙齿有好处.

1、用盐或茶叶
2、人一般只有28颗牙齿
3、牙垢本身就不干净加上它沾在牙齿上，成了细菌的依附物。
4、一般的食物对牙齿都没有什么坏处，只要你在睡觉前，不吃东西，防止长蛀牙。

1.好像是用树枝片来当牙膏吧,用口来嚼,槟榔也是吧,
2.乳牙是28颗,成人后大部分人会长,也就是32颗,
3.牙垢在口腔停留过久就会发酵,为细菌提供了很好生存环境,所以细菌就可以繁殖,
4.槟榔可以预防龋齿,含维C的水果可以美白牙齿,

1.人类在没有牙膏之前用树叶,也正是因为人咀嚼树叶后来便发明了牙膏
2.一般都是32颗
3.因为每天吃饭有食物渣滓残留在牙缝间,所以会产生细菌
4.淡茶水会对牙齿有好处.

1.用盐的