Unknown bad habit causes tooth decay 导致蛀牙的坏习惯
<p><span word="Unknown">Unknown</span> <span word="bad">bad</span> <span word="habit">habit</span> <span word="causes">causes</span> <span word="tooth">tooth</span> <span word="decay">decay</span> 导致蛀牙的坏习惯</p><p>本集内容 <span word="Unknown">Unknown</span> <span word="bad">bad</span> <span word="habit">habit</span> <span word="causes">causes</span> <span word="tooth">tooth</span> <span word="decay">decay</span> 导致蛀牙的坏习惯</p><p>学习要点 有关“<span word="tooth">tooth</span> <span word="decay">decay</span> 蛀牙”的词汇</p><p>边看边答 <span word="What">What</span> <span word="does">does</span> <span word="Rachel">Rachel</span> <span word="do">do</span> <span word="that">that</span> <span word="causes">causes</span> <span word="damage">damage</span> <span word="to">to</span> <span word="her">her</span> <span word="teeth">teeth</span>?</p><p><span word="acidic">acidic</span></p><p>酸性的</p><p><span word="erode">erode</span></p><p>腐蚀，侵蚀</p><p>你知道吗？ <span word="Humans">Humans</span> <span word="have">have</span> <span word="two">two</span> <span word="sets">sets</span> <span word="of">of</span> <span word="teeth">teeth</span>. <span word="The">The</span> <span word="first">first</span> <span word="set">set</span> <span word="of">of</span> 20, <span word="which">which</span> <span word="are">are</span> <span word="informally">informally</span> <span word="referred">referred</span> <span word="to">to</span> <span word="as">as</span> ‘<span word="milk">milk</span> <span word="teeth">teeth</span>’, <span word="are">are</span> <span word="lost">lost</span> <span word="in">in</span> <span word="childhood">childhood</span>. <span word="The">The</span> <span word="adult">adult</span> <span word="set">set</span> <span word="has">has</span> 32 <span word="and">and</span> <span word="consists">consists</span> <span word="of">of</span> <span word="four">four</span> <span word="incisors">incisors</span>, <span word="two">two</span> <span word="canines">canines</span>, <span word="four">four</span> <span word="premolars">premolars</span> <span word="and">and</span> <span word="six">six</span> <span word="molars">molars</span> <span word="in">in</span> <span word="each">each</span> <span word="jaw">jaw</span>.</p><p>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。</p><p>问题答案 <span word="Rachel">Rachel</span> <span word="holds">holds</span> <span word="the">the</span> <span word="drink">drink</span> <span word="in">in</span> <span word="her">her</span> <span word="mouth">mouth</span> <span word="longer">longer</span> <span word="than">than</span> <span word="the">the</span> <span word="average">average</span> <span word="person">person</span>, <span word="which">which</span> <span word="exposes">exposes</span> <span word="her">her</span> <span word="teeth">teeth</span> <span word="to">to</span> <span word="the">the</span> <span word="liquid">liquid</span> <span word="for">for</span> <span word="more">more</span> <span word="time">time</span>.</p>
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