多项选择题
A.AMI
B.ESF
C.DUS
D.SSM
E.B3ZS
F.B8ZS
单项选择题 Which timing mode is appropriate for a SONET NE that is adjacent to a SONET NE using BITS-1 timing source?（）
单项选择题 If node 2 is accepting line timing from node 1, node 2 will send （）to node 1 as its SSM message.
单项选择题 SONET Code Violations (CVs) totals in the PM tables are actually an accumulation of the number of （）.