广域网提供的虚电路服务是无连接的。（ ）

相关题目

• In the microwave transmission,the rain attenuation are calculate
• Digital microwave systems can be used for telephone, data, image
• The remote communication of the microwave relay communication is
• In the digital microwave communication system, in order to meet
• What's function of the duplexer in the microwave communication s