第二级寻线机的英文

secondary line switch

• 第二级:    second stage
• 寻:    look for; search; ...
• 线:    thread; string; wi ...
• 机:    machine; engine

例句与用法

1. Invention of out - going secondary line switch , resulting in economy of inter - office trunks . first used at san francisco
   发明外向第二级寻线机，提高了局间中继的收益，并首次在旧金山使用。