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.

74（）

A．FDDI

B．HDSL

C．ADSL

D．CDMA

关于超临界流体提取法叙述正确的是（）

A.超临界流体黏度高，扩散性低

B.超临界流体密度低

C.常使用的是超临界H₂O流体

D.适用于水溶性成分的提取

E.适用于热敏性成分的提取