一般来说，如果网络的利用率超过了40％，并且碰撞率大于10％，网络就可以选用交换机来改善网络状况。（）
参考答案：对
Which of the following people would find "taking it easy" stressful
A．Construction workers.
B．Business executives.
C．Farm workers.
D．Truck drivers.
发生短路故障对系统有何危害？
