单项选择题
Which timing mode is appropriate for an SDH NE that is adjacent to an SDH NE Bits-1 timing？ （）
A. DUS B. line timing C. loop timing D. internal timing E. through timing
多项选择题 WhichtwocanbetransportedinoneAU-4？（）
单项选择题 HowisSNCPandMS-SPRingtrafficreroutedduringaprotectionswitchwhenacompletefibercablecutoccurs？（）
单项选择题 AVC-4-4cconsistsof（）.
