In order to realize safety production in coal mine, ventilation system must be set up.

为了实现煤矿安全生产，各矿必须建立稳定的矿井通风系统。

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In order to realize safety production in coal mine, ventilation system must be set up.

为了实现煤矿安全生产，各矿必须建立稳定的矿井通风系统。

youdao