Freezing mud that reached track level could derail a train, and rock salt kept the mud soft.

铁轨周围结冰的泥土会造成火车脱轨，岩盐可以使泥土保持松软。

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Freezing mud that reached track level could derail a train, and rock salt kept the mud soft.

铁轨周围结冰的泥土会造成火车脱轨，岩盐可以使泥土保持松软。

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