Therefore, before an electric service is started, the line must be charged with electricity. The necessary current may be carried in a third rail, just outside one of the normal rails.

 
  • 因此,在供电前,必须安装好电线,或者,电流可以通在第三根铁轨里,它位于某一条普通铁轨的外侧。
今日热词
目录 附录 查词历史