PartⅠ Sentences Commonly Used
1.Metro signaling is a complicated and amazing system.
地铁信号是一个复杂而神奇的系统。
2.UK has a longer history of metro signaling than any other country.
英国的地铁信号历史比其他任何国家都长。
3.Metro signaling has similarities with railway signaling.
地铁信号与铁路信号相似。
4.To prevent any train delays，accidents，even casualties，it is important that a signaling system operated by a group of well-trained people.
为防止列车晚点、事故甚至人员伤亡，由一群训练有素的人员来操作信号系统是非常重要的。
5.The most critical role that signals play in the metro system is to locate the whereabouts of trains and to protect trains from collisions.
信号在地铁系统中发挥的最关键作用是定位列车的位置，保护列车免受碰撞。
6.The most important components in a metro signal system are its electromechanical relays.
地铁信号系统中最重要的部件是机电继电器。
7.If a metro signal fails，the signaling light will go to red and the train will stop until the failures are resolved.
如果地铁信号失败，信号灯将变为红色，列车将停止，直到故障得到解决。
8.Most of metro signals have Green on top，Yellow in the middle and Red on the bottom.
大多数地铁信号灯顶部为绿色，中间为黄色，底部为红色。