单项选择题
A.减少信号衰减 B.减少电磁干扰辐射 C.减少物理损坏 D.减少电缆的阻抗
A.6 B.12 C.15 D.18
A.127.13.214.254 B.305.299.13.1 C.227.405.13.112 D.105.14.155.12