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当前学科：初级通信工程师
题目：
单选题
电信网（Telecommunication Network）是多个用户电信系统互联的通信体系，是由终端设备、传输设备、（）等基本要素组成的综合系统。
A
变换器
B
控制设备
C
路由设备
D
交换设备
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