电报交换机

例句：

1. 1. The telegraph was invented to transmit messages quickly.
   电报被发明用来快速传输信息。
2. 2. He sent a telegram to his friend in another city.
   他给另一个城市的一个朋友发送了一封电报。
3. 3.The telegraph was the first communication method invented by humans.
   电报是人类发明的第一种通信方式。