The oral surfaces covered in keratinized epithelium include the hard palate, the dorsal surface, or top, of the tongue, and the gingiva.

口腔表面由角化上皮覆盖的结构包括硬腭、舌的背侧面（或上面）与牙龈。

With a ch, the part of the tongue touches the hard palate and then releases slowly as in words like 'church', and 'chew' and 'chalk'.

ch 的发音方法是舌头的一部分接触硬腭，然后缓慢地释放，就像“church”、“chew”和“chalk”这样的单词一样。