Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions from 28 to 32.

          Not so long ago, people only used the telephone to make phone calls. Now, thanks to computers, people use their phones to do much more. They can bank by phone, rent videos by phone, and even shop by phone. It is also possible to send letters and reports by faxing them over telephone lines. People can even use their phone lines to send messages from one computer to another computer by electric mail, or e-mail.

But you don’t need to be at home or at the office to use the phone anymore. You can carry a cellular phone in your pocket or keep one in your car. With a cellular phone, anyone who can talk and walk can also phone and walk. You don’t have to look for a pay phone to make a call anymore. Now you can take your calls with you everywhere.

The main topic of the passage is______