This paper discusses the subject of pollution prevention for ship ballast water system, presents some idea of ballast water continuous replacement system design, which requires further verification.

该文对船舶压载水系统防污染的有关问题进行了探讨，给出了压载水连续更换系统设计的一些思路，这些探讨有待于实践的进一步检验。

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The large track maintenance machines were used in the railway engineering construction of replacement for ballast on the Guangzhou-Maoming railway line.

文章介绍了有关在广州-茂名铁路运用大型养路机械进行更换石碴施工的技术和经验。

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