复用段SD保护倒换的两个条件是(),这两个告警的误码门限缺省分别是10-6、10-3。
参考答案:B2_SD和B2_OVER
数轴上的点A到原点的距离是3,则点A表示的数为[ ]
A.3或-3
B.6
C.-6
D.6或-6
Lang Lang is one of ______ and most famous pianists ______ our time. [ ]
A. youngest; of
B. the youngest; of
C. younger; at
D. younger; in