学习笔记：
fingernail：手指甲
例句：I have the fingernail clippers.
我有指甲钳。
knuckle：指节
例句：Our fingers bend at the knuckle.
我们的手指在指关节处弯曲。
thumb：拇指
例句：The little child took her ear between her thumb and forefinger and tugged it playfully.
小孩用大拇指和食指捏住她的耳朵，拉着玩。
finger：手指
例句：A mantis nipped my finger.
螳螂挟住我的手指。
palm：手掌
例句：Buddhist monk sat with folded palms.
和尚合掌打坐。