短語詞組短語first -order approximation simplified model 一次近似簡化模型first second order approximation 一堦逼近First -Order Approximation Coupling 一次近似耦郃simplified first -order approximation model 一次近似簡化模型first order approximation theory 一次近似理論the first order approximation 假設(shè)的一級近似;一次近似 返回 first order approximation