她滑倒了，摔在了她的臀部上。

She slipped and fell on her ___bottom.

有两个人抓着我的手臂，梯子下第三个人抓着我的臀部。

There were two people holding my arms, and the third one on the ladder below me was holding my ___bottom.

他坐在一把硬椅子上，臀部疼。

He sat down on a hard chair and his ___bottom hurt.