|
Unknown bad habit causes tooth decay 导致蛀牙的坏习惯 本集内容 Unknown bad habit causes tooth decay 导致蛀牙的坏习惯 学习要点 有关“tooth decay 蛀牙”的词汇 边看边答 What does Rachel do that causes damage to her teeth? acidic 酸性的 erode 腐蚀，侵蚀 你知道吗？ Humans have two sets of teeth. The first set of 20, which are informally referred to as ‘milk teeth’, are lost in childhood. The adult set has 32 and consists of four incisors, two canines, four premolars and six molars in each jaw. 人类有两副牙齿。第一副20颗牙齿通常被称为“乳牙”，在孩童时代会全部脱落。成年人有32颗牙齿，其中上下额分别都有4颗门牙，2颗犬齿，4颗前臼齿和6颗臼齿。 问题答案 Rachel holds the drink in her mouth longer than the average person, which exposes her teeth to the liquid for more time. | 
