他们说，他们必须挖掘该污水管道进行必要的维修和更换，而该工程将定于本周即将展开。
They said they will have to dig up a long portion of the sewer pipe to make the necessary repair and replacement.
建议在热水和冷水管线上安装管接头，以方便热水器的维修或更换。
The installation of unions in both the hot and cold water supply lines is recommended for ease of removing the water heater for service or replacement.
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