在所有不同的深度都有宽阔、狭窄的通道，就像石灰岩中的地下隧道。

There are wide passages, narrow ones at all different depths, like underground tunnels in the limestone.

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连接协议：该协议多路传输加密隧道到多个逻辑通道，通过用户认证协议运行。

Connection protocol: This protocol multiplexes the encrypted tunnel to numerous logical channels, running over the User Authentication protocol.

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严禁擅自打开警示绳或越过安全黄线，进入轨道交通道床、隧道，这种行为不仅会严重威胁您的生命安全，也将对运营安全和公共安全造成严重影响。

Jumping into the tunnel is prohibited. This behavior is very dangerous and will severely disrupt the subway system.

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