爬行动物的泄殖腔兼具排泄和繁殖功能。

The ___cloaca in reptiles serves both excretory and reproductive functions.

这座古城的地下排水系统通过一条巨大的暗渠将废水排入河中。

The ancient city's drainage system directed wastewater into the river through a large ___cloaca.