1. An audio/video reproducing system, comprising: a server including a database that stores a plurality of complete pieces of audio or video data, the server being configured to store partial pieces of audio or video data onto a detachable recording medium, wherein a size of each partial piece of data stored on the detachable recording medium is determined based on a first division pattern and a second division pattern, the first and second division patterns determined in accordance with a communication speed between the server and the detachable recording medium, and in accordance with a time required to authenticate identification codes to effect the storing of the data; the first division pattern corresponding to an initial predetermined period of time corresponding to the data to be stored, and having a plurality of sequential time slices, wherein an amount of data stored from a first time slice to a last time slice decreases in a step-like manner; the second division pattern corresponding to data to be stored after the initial predetermined period of time, and having a plurality of sequential time slices, wherein an amount of data to be stored is stored at a constant rate; and an audio/video reproducing device configured to (1) subsequently read a partial piece of audio or video data stored on the detachable recording medium and (2) determine whether the partial piece of audio or video data read from the detachable recording medium is complete, wherein when the audio/video reproducing device determines that the partial piece of audio or video data is not complete, the audio/video reproducing device obtains lacking data from the database through communication connection with the server, the lacking data being the rest of the audio or video data, and combines the partial piece of audio or video data read from the detachable recording medium with the lacking data retrieved from the database to reproduce a corresponding complete piece of audio or video.