摘要： Which two statements are true about broadband cable (HFC) systems? (Choose two.) A. Cable modems only operate at Layer 1 of the OSI model. B. Cable modems operate at Layers 1 and 2 of the OSI model. C. Cable modems operate at Layers 1, 2, and 3 of the OSI model. D. A function of the cable modem termination system (CMTS) is to convert the modulated signal from the cable modem into a digital signal. E. A function of the cable modem termination system is to convert the digital data s 阅读全文