Traditional Internet access methods like dial-up were so slow that host computers were connected to the dial-up （71） at the customer premise over slow （72） ports.PPP was designed to run directly over these serial links. But with the advent of broadband Internet（73） technologies such as ADSL and cable modems there has been a considerable increase in the bandwidth delivered to the end users. This means that the host computers at the customer premise connect to the （74） or cable "modem" over a much faster medium such as Ethernet. It also means that multiple （75） can connect to the Internet through the sameconnection.

A．parallel

B．digital

C．serial

D．variable

我国大多数中心城市都已经开通了数字有线电视服务，且开始播出高清电视节目。所谓高清晰度电视（HDTV）其画面分辨率是（）。

A．640×480

B．1024×768

C．1920×1152

D．720×576