简要说明企业的计划层次及其区别？

h is not stteds the feture of expert systems Expert systems cnlwys reson with metknowledge. B．Expert systems use knowledge rther thn dt to control the solution process. C．Expert systems cn explin how prticulr conclusion is reched. D．Expert systems use symbolic representtions for knowledge.A．Expert systems can always reason with metaknowledgeB．Expert systems use knowledge rather than data to control the solution process．C．Expert systems can explain how a particular conclusion is reacheD．Expert systems use symbolic representations for knowledgE．