A.1060 B.1070 C.1080 D.1090
A.多種業(yè)務(wù)的兼容性 B.數(shù)字傳輸 C.標(biāo)準(zhǔn)化的接口 D.費(fèi)用昂貴
A.2M B.8M C.34M D.140M