单项选择题
A.方波 B.三角波 C.正弦波 D.矩形波
A.单模光纤、多模光纤 B.LC/SC C.千兆光纤、万兆光纤 D.尾纤、光缆
A.255.255.255.240 B.255.255.255.252 C.255.255.255.248 D.255.255.255.0