tóu fa hé jiǎ jiá de zhǔ yào chéng fèn dōu shì jiǎo zhì sù，hán liàng yuè gāo zhì dì yuè yìng。

头发和指甲的主要成分都是角质素，含量越高质地越硬。

The main component of both hair and nails is keratin; the higher the keratin content, the harder the texture.