Which statement correctly describes enabling BPDU guard on an access port that is also enabled for PortFast?()
A. Upon startup, the port transmits 10 BPDUs. If the port receives a BPDU, PortFast and BPDU guard are disabled on that port and it assumes normal STP operation.
B. The access port ignores any received BPD
C. If the port receives a BPDU, it is placed into the error-disable state.
D. BPDU guard is only configured globally and the BPDU filter is required for port-level configuration.
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对于微管的超微结构叙述错误的是()。
A. 微管是中空的圆筒状结构
B. 微管直径22—25纳米
C. 微管由同二聚体微管蛋白亚单位所构成
D. 微管有13根原纤维构成
肝炎病毒只有甲、乙、丙、丁型四种病毒。
A. 正确
B. 错误
20世纪30年代,()首次提出了分面组配的理论,并编制了第一部分面分类法()。
当出口外50m范围内无建筑物.出口外20m处的微压波峰值大于50pa时,应设置缓冲结构。
A. 正确
B. 错误