https://online2.tingclass.net/lesson/shi0529/0009/9907/168.mp3
https://image.tingclass.net/statics/js/2012
講解文本：
grind one's teeth 磨牙
grind 磨，碾
Some people grind their teeth while they are asleep.
有些人睡覺時磨牙齒。
My roommate Jack always grinds his teeth in his sleep, which is a totally disaster.
我室友Jack喜歡睡覺磨牙，這對我就是個災(zāi)難。
瘋狂練習(xí)吧!
