through the income factor, technological factor, classified standard and the colony of achievement state, analyzing the inherent law of the development of trade pattern;
通过收入因素、技术因素、分类标準和业态群体,分析零售业态发展的内在规律;
it makes comparative analysis about parts of gb150 welding connection classified standard and international standard. it also makes improvable suggestions of pressure containers' testing criterion.