《科技英语阅读手册》（郭坤编）在讲到“定语从句与先行词之间的间隔”一节时给出的一个例句：

By catching the mixture of water and material as it comes out of the casing one may obtain samples of a portion of the material passed through which is both disturbed and washed .接取套管中流出的水和材料的混合物，即可获得流过管道那一部分材料的试样；该材料此时是非原状的，并且是经受过冲洗的。

本句过去分词 passed through 作定语，修饰 material，使得先行词 material 与定语从句 which is both disturbed and washed 分隔。

但我觉得 passed through 后似乎少个 the pipe ，而且译文中有“管道”一词。不知我的想法对否，请专家指教，谢谢！