Vision-phones(可视电话)
Radio，telephone and television are widely used in the world. When you switch on the radio, you can listen．But when you use a telephone，not only can you listen to others but also you can chat with them，however, you can’t see anything at all. Television 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．
Vision-phones can be of great use when you have something to show the person whom you are calling，It may also have other uses in the future．Some day you may be able to call up a library and ask to read a book right over your vision-phone. You may be able to do some shopping through it, too. Perhaps in the near future, vision-phones will come into wide use in our everyday life.
According to the passage, we can guess that the_______ was invented last.

A．radio

B．vision-phone

C．telephone

D．television

Maybe the vision-phone can take the place of______ some day.

A．the telephone

B．the radio

C．the television

D．all the above

In the future, you can use a vision-phone to ________ 

A．ask an assistant to read a book for you

B．read a book

C．ask an assistant to bring you a book

D．ask an assistant to do some shopping for you