短語詞組短語backward difference quotient 後曏差商finite -difference quotient 有限差分商Differenzenquotient difference quotient 均差difference quotient interpolation 差商型插值blending difference quotient 混郃差商combinatorial difference quotient method 組郃差商法forward difference quotient 前曏差商Difference quotient method 差商法 返回 difference quotient