水平定向钻孔(HDD)常常是管道穿越河流或湿地这类障碍优先选用的方法。插图表示河流穿越的典型情况。
HDD is often the preferred method for constructing the pipeline across such obstacles as streams or wetlands. (See inset diagram.) Here is shown a typical river crossing.
下面的插图表示，年底各方面的三轮车后面。
The illustrations below represents all aspects of the trike rear-end.
下面的插图表示，年底各方面的三轮车后面。
The illustrations below represents all aspects of the trike rear-end.
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