下列有关感受阈的论述，错误的是（）

A. 单纯收缩期高血压少见
B. 老年高血压波动大，且易出现直立性低血压
C. 老年人高血压常有不同程度的心、脑、肾等靶器官损害
D. 以高血压为主的临床表现的代谢综合征发病率高

A. 正确
B. 错误

A. In a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.
B. In an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP field.
C. In an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.
D. The differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.
E. The 802.1Q standard uses a three bit field referred to as the user priority bits （PRI） to mark packets as belonging to a specific Co