Tóm tắt nội dung: Exercise 1. Read the following passage then answer the questions. ANALOGUE AND DIGITAL NETWORKS Digital technology in the telephone network is nothing new. Take all the relays in older exchanges as an example. Relays are either "off" or "on", and there is no state in between these. Suitable combinations of relays could build up and "remember" numbers - perhaps a far-fetched example, but in was digital, so it will serve! What is new is the transfer of speech digitally. In other words, the sound we...