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．cables

B．hosts

C．servers

D．modems

驾驶机车、动车组、自轮运转特种设备的人员，必须持有国家铁路局颁发的（）。变更驾驶机（车）型前，必须经过相应的技术培训并考试合格。

A、上岗证

B、驾驶证

C、执照