What is the purpose of the STP PortFast BPDU guard feature? ()
A. enforce the placement of the root bridge in the network
B. ensure that a port is transitioned to a forwarding state quickly if a BPDU is received
C. enforce the borders of an STP domain
D. ensure that any BPDUs received are forwarded into the STP domai
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()选择硐室施工方法主要要考虑围岩的稳定性,断面大小和服务年限等因素。
A. 正确
B. 错误
整体搬迁钻机时,首先要察看好行驶路线,道路坡度不得大于()。
水喷雾灭火系统用于其他系统防护时,不应大于()s。
A. 100
B. 750
C. 300
D. 400
水泥的品种繁多,按用途及性能分为通用水泥、专用水泥和特征水泥。
A. 正确
B. 错误