Piggery is cement floor, sit boreal Xiang Na sneaks away brae, excrement and urine can pass Naduan leakage of an alveolus path takes subterranean firedamp poll.

• 猪圈是水泥地面,坐北向南一溜斜坡,粪便可以通过南端一个小孔道漏进地下沼气池。