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 Copper finger caps are used during the brewing process at Baoyuan Vinegar Workshop in Qingxu county, North China's Shanxi province, Sept 5, 2013. [Photo by Guo Rong/chinadaily.com.cn]  | 
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 The smoking fermentation section of Baoyuan Vinegar Workshop in Qingxu county, North China's Shanxi province, Sept 5, 2013. [Photo by Guo Rong/chinadaily.com.cn]  |