常见的把压力信号转换为电信号的（），一般也称为压力开关。
A．驱动装置
B．检漏装置
C．安全泄放装置
D．信号反馈装置
参考答案：D
In low-speed network，it is usually adequate to wait for congestion to occur and then react to it bytelling 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 offeredand the service expected．
（72）处填（）。
A．packets
B．cells
C．message
D．files
如何确认操作权？
