In China,SDH system is adopted by Post and Telecommunication Ministry of China and Federal Telecommunication Corperation of China, so as to replace PDH system and expand capacity for better service.是什么意思_In China,SDH system is adopted by Post and Telecommunication Ministry of China and Federal Telecommunication Corperation of China, so as to replace PDH system and expand capacity for better service.在線翻譯_英語_讀音_用法_例句