Which of the following describes the roles of devices in a WAN?（） ["A CSU\/DSU terminates a digital local loop","A modem terminates a digital local loop","A CSU\/DSU terminates an analog local loop","A modem terminates an analog local loop","A router is commonly consideredaDTEdevice","A router is commonly considereda DCE device"]
节理组
鲕粒
异步电动机通过坐标变换简化其数学模型时，若以静止正交坐标为变换方向，定转子绕组的变换方式有何不同？
于某投保了一份保额10万元的意外伤害保险。一天，于某到某名山旅游时不幸被车撞死。事后肇事司机赔偿8万元，有人认为根据代位原则，这笔赔款应该归保险公司。这种说法正确吗？为什么？
简述生态平衡的含义？
