坐在硬板凳上很容易让屁股酸痛。

Zuò zài yìng bǎndèng shàng hěn róngyì ràng pìgu suāntòng.

Sitting on a hard bench for a long time can make your buttocks sore.

小孩不小心摔了一跤，屁股都摔疼了。

Xiǎohái bù xiǎoxīn shuāi le yì jiāo, pìgu dōu shuāi téng le.

The child accidentally fell down and hurt his bottom.

这把椅子太硬了，坐久了屁股会很不舒服。

Zhè bǎ yǐzi tài yìng le, zuò jiǔ le pìgu huì hěn bù shūfu.

This chair is too hard; if you sit for a long time your bottom will feel very uncomfortable.