41.二线连接 a. data traffic b. end office c. two wire connection 答案 42.数据流量 a. data traffic b. tandem switch center 答案 43.全球通信 a. interface equipment b. global communication c. communication carriers 答案:b 44.脉码调制 a. pulse code modulation b. voice encoding c. open network 答案: 接口设备 a. switching equipment transmission medium c. interface equipment 答案:c 46.综合业务数字网 0 end-to-end digital connectivity b. international organization for standardization c. integrated services digital network 答案 47.通信载体 a. communication carriers b. transmission medium c. interface equipment 答案 48.系统结构 L. infrastructure c. flexibility d. basic access 答案 a 49.蜂窝式移动电话 a. cellular switch b. cellular mobile telephone c. cellular site 答案:b 50.数据传输 a. data transmission b. transmission error c. error flag 答案 51.传号电平 a. space level b. logical level C. mark level 答案:c 52.接收机的定时 a. intersymbol space b. serial interface c. receiver timing 答案:c 53.明显的缺点 a. transmission error b. obvious disadvantage41.二线连接 a. data traffic b. end office c. two wire connection 答案：c 42.数据流量 a. data traffic b. tandem switch c. toll center 答案：a 43.全球通信 a. interface equipment b. global communication c. communication carriers 答案：b 44.脉码调制 a. pulse code modulation b. voice encoding c. open network 答案：a 45.接口设备 a. switching equipment b. transmission medium c. interface equipment 答案：c 46.综合业务数字网 a) end-to-end digital connectivity b. international organization for standardization c. integrated services digital network 答案：c 47.通信载体 a. communication carriers b. transmission medium c. interface equipment 答案：a 48.系统结构 a. infrastructure c. flexibility d. basic access 答案：a 49.蜂窝式移动电话 a. cellular switch b. cellular mobile telephone c. cellular site 答案：b 50.数据传输 a. data transmission b. transmission error c. error flag 答案：a 51.传号电平 a. space level b. logical level c. mark level 答案： c 52.接收机的定时 a. intersymbol space b. serial interface c. receiver timing 答案：c 53.明显的缺点 a. transmission error b. obvious disadvantage