针对北京地铁4号线及其延伸，讨论线路延伸工程中信号系统适用的两种实施方案。
Considering the signaling system project for Beijing subway Line 4 and its extension, two different implementation options are discussed.
针对北京地铁4号线及其延伸，讨论线路延伸工程中信号系统适用的两种实施方案。
Considering the signaling system project for Beijing subway Line 4 and its extension, two different implementation options are discussed.
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