E-mail or electronic mail, is considered as the modern communication in the new age. It is carried out in computers all over the world by millions of users. In this invisible world as many people call it, the users can send and receive letters to and from every corner of the earth. They share thoughts with pen pals（笔友）in New Zealand, ask strangers in Bombay（孟买）questions, debate with businessman in Manhattan. All of these are just happening in computers as fast as the travelling of the light, no writing and speaking, no paper and stamps are necessary.
E-mail is a pipeline to thousands of experts on everything; it is a means of meeting people with similar interests or problems. But it is not a live talk－a real conversation like those in telephones. E-mailers compose letters at leisure on their computers, then send them by phone line to an on-line service, and then they go forward to the right place. A response can be back within hours, depending on how often the recipient（接受者）checks in.
A vast global networks of on-line services for E-mail has been built. A lot of people are regularly using this service in the USA. People believe that E-mail, the computerized exchange, would create friendship and business developments, and would change people's life in the world.
Which of the following expression is not for E-mail?
A.Communication in new age
B.Invisible world
C.A live talk
D.Computerized exchange