循环经济包含三个层次：第一层次是企业内的物质循环-----符合循环经济发展的典型企业。第二层次是企业之间的物质循环-----符合循环经济发展要求的生态工业（农业）园区。第三层次是包括生产和消费的整个过程的物质循环-----资源节约型、循环友好型城市。
【正确答案】：译：Circular economy has three levels: the first is to circulate the materials within a firm-----a particular firm that is up to the criteria of the developing circular economy. The second level is to circulate among firms-------the eco-industrial ( agricultural) parks. The third level is the whole process of material circulation including production and consumption------ a resource saving and environmentally well-being city.
