未知题型 如图1-1所示为网络地址转换(NAT)的一个实例。为②的方格中的内容应为______。

单项选择题 摩拜单车和滴滴出行都属于什么商业模式？（）

未知题型 In low - speed network ,it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high - speed networks, this approach often works poorly, because in the(71)between sending the notification and notification arriving at the source, thousands of additional(72)may arrive. In ATM network , a major tool for preventing(73)is(74)control. When a host wants a new virtual(75),it must describe the traffic to be offered and the service expected.