That's because hydrogen peroxide soaks through the protective outer coating of enamel and into the softer layer of dentin underneath, irritating the nerve-rich dental pulp at the core.
这是因为过氧化氢会渗入釉质的外部保护层并进入牙质下面的较为柔软的一层，刺激神经组织比较多的牙髓。
The spirit of playing is childrens spirit, and soaks through childrens life.
游戏精神是儿童文学的基本美学精神之一，它在儿童文学中占据着举足轻重的地位。
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