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floating head backing device

英 [ˈfləʊtɪŋ hed ˈbækɪŋ dɪˈvaɪs] 美 [ˈfloʊtɪŋ hed ˈbækɪŋ dɪˈvaɪs]

浮动背衬环，浮头勾圈

化学

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