The USA, Japan and European countries have taken the superior position in this field, as they are using satellite, telephone line and cable as communication media and obtained successful results.

有些国家如美国、日本及欧洲的一些国家在这方面处于领先地位，使用了卫星、电话线和光缆等传输介质，并取得了成功。

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The USA, Japan and European countries have taken the superior position in this field, as they are using satellite, telephone line and cable as communication media and obtained successful results.

有些国家如美国、日本及欧洲的一些国家在这方面处于领先地位，使用了卫星、电话线和光缆等传输介质，并取得了成功。

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