This kind of identifications demands a great deal of training and practice experiences, at the same time, the people who examines downs, must know well about the characteristics of goose down , duck’s down, c.
这种鉴定需要大量的训练和实践经验,检测人员必须对水禽毛中鹅绒、鸭绒,陆禽毛中的鸡毛、鸽子毛等的形态特征有一个充分的了解。