用户交换机的实装内线分机限额,通常为交换机容量门数的()。
A.100%
B.90%
C.80%
D.70%
参考答案:C
---Hello, May I speak to John?
--- , please call back later.
A.Wait a minute
B.I’ll look for him
C.Sorry, he isn’t in
D.I’m busy now
单双线半自动闭塞色灯电锁器联锁接发列车作业标准是()。