Radio, telephone and TV are widely used in the world. When you turn on the radio, you can listen. But when you use telephone, not only can you listen to others but also you can chat with them, however, you can't see anything at all. TV is much better than both of them. People can watch TV and listen to it, but they can't take part in what they see. Today, some people are using a type of telephone called vision-phone . With it, two people who are talking can see each other. It is better than radio, telephone or TV. Vision-phones can be of great use when you have something to show the person whom you are calling. It will be helpful in people's life. Some day you may be able to call up a library and ask to read a book on your vision-phone. You may be able to do some shopping too. Perhaps in the future, people will use vision-phone. ,. Maybe the vision-phone can take the place of   _  some day.
the radio the telephone the TV all the above