这课本里面分为四个单元。

Zhè kèběn lǐmiàn fēnwéi sì gè dānyuán.

This textbook is divided into four units.

我住在这个公寓楼的三楼单元。

Wǒ zhù zài zhè gè gōng yù lóu de sān lóu dān yuán.

I live in the third unit of this apartment building.

这个房子有五个单元。

Zhè gè fáng zi yǒu wǔ gè dān yuán.

This house has five units.