原因如下：首先，网络广播支持声音、文本和视频。

The reasons are as follows: first of all, the network broadcast supports voice, text and video.

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数据广播是一种能将文本、图形、视频、音频、数据等传输到机顶盒等智能设备的一项技术。

Data broadcasting is a technique that can transmit text, graphics, video, audio, data to an intelligent equipment, such as STB.

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数据广播系统能够为用户带来更多的图形、文本、游戏、数据下载、在线升级等功能，在网络支持的情况下还能够实现交互功能。

Data broadcasting system bring more functions for user, such as graphics, text, online upgrades, games and data download, and etc. And it can also support interactive features if network supported.

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