用到了吸收定律原式展开=(A非)×B+A×C+B×C (A×非A=0)=(A非)×B+A×C+A×B×C+(A非)×B×C (将B×C按A展开为两项)=(A非)×B+A×C [(A非)×B吸收了项(A非)×B×C；A×C吸收了项(A非)×B×C]
