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 same connection.

75（）

A．cables

B．hosts

C．servers

D．modems

假定在扩大再生产起始的第一年，社会总产品的构成是Ⅰ（4000c+1000v+1000m）=6000；Ⅱ（1500c+750v+650m）=2900，又假定资本技术构成不变，资本家仅用剩余价值中的500来作为个人消费，其余部分用于扩大再生产，则部门间交换的价值总额是（）

A．1600

B．2000

C．1500

D．3000