Ans. The first revolution is a symbol of an object that is used to convey an idea. Symbol of the sound. It's easier to communicate.
The second revolution is the printing ,In the world started to develop technologies such as computers, printers, phones, and it can be ordered immediately.
The third revolution is digital computers technology is the equipment that is necessary in the daily lives for everyone. It processes , save information and transmits. Both easy, fast and suitable for today's world. (Page 16 - 18)