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The telegraph is an electrical device that can transmit text messages. -
The telephone works sending signd to telecommunication towers. We use them to communicate among us without the need of being close. -
The radio sends signs through the electromagnetic waves. -
The television is a system of transmission and reception of images, sounds. -
The computer is an electronical system that can store and process data. -
The tablets use a touch screen for write and surf faster. -
The mobile phone can call, send text messages, surf in internet...