A. 正确 B. 错误
A. CRC校验错误 B. E1收信号帧失步告警 C. 以太网口检测到冲突 D. 表示以太网口为全双工工作模式
A. middle of the channel B. starboard side of the channel C. port side of the channel D. side of the channel that has the widest tur