2500+子架IU2板位和（）板位共用VC4总线。

A.1个VC4
B.2个VC4
C.4个VC4
D.8个VC4

A.EXT-SYN-LOS
B.SYNBAD
C.LTI
D.SYNC-LOS

A.SCC上报“path-mon-fail”
B.SCC上报“hard-bad”
C.XCS上报“hard-bad”
D.S16上报“path-mon-fail”