穿过房屋下面的排水管道，必须使用铸铁管，这是排水管所用的最昂贵的材料。

Drains which pass under a house must be of cast iron, the most expensive material for pipe drains.

youdao

穿过房屋下面的排水管道，必须使用铸铁管，这是排水管所用的最昂贵的材料。

Drains which pass under a house must be of cast iron, the most expensive material for pipe drains.

youdao