说明：  信号放大器：在一个分布式网络中，资源被从生产地送往其他地方。当信号在网络中传输时，其性能的木一个后几个方面可能会有所损失或衰减。为了保证信号衰减不超过容人值，应在网络中适当的位置防止信号放大器。
(Signal Amplifiers : in a distributed network, resources from production to be sent to other places. When the signal transmission network, the performance of a wood after several likely to be loss or attenuation. To ensure that signal attenuation value not exceeding tolerance, the network proper place to prevent signal amplifier.)