最早采用这种机制的主要是一些网络资源有限的运营商，比如卫星网络，手机网络等等，不过后来这种机制逐渐被推广到其它的有线运营商中去。

Though it originated amongst ISPs with limited resources available (Satellite and Cellular come to mind), it is spreading to the largest of networks, such as cable and DSL.

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而网络学习环境是能够自主获得的综合了课程材料，在线交流渠道，多媒体和其它具有交际特色的网络资源。

While a networked learning environment is an autonomously accessible web resource that combines hypertext course materials, online communication channels, multimedia and other interactive features.

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虚拟资源网可使控制组件网络化，每个组件有唯一地址，网络中的其它资源不需要知道它的确切位置，只根据网络资源名就可以访问它。

VRN considers control components as resource, each component has unique address, and other resources access it only through its network source name and need not know where it lies exactly.

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