四: four阶: steps; stairs方程: equation二阶方程: second order equation; second-order equation高阶方程: equation of higher order高阶方程式: equation of higher order一阶方程: first order equation一阶方程, 一次方程: first-order equation四阶微分方程: fourth-order differential equation四阶: quadravalence一类四阶偏微分方程系统的控制问题: control problem for a calss four-order differential equations system二阶方差: second order deviation第四阶段: phase four - programme suspension四阶段提交: four-phase commitment四阶矩量: fourth moment四阶魔方: rubik's revenge四阶张量: fourth-order tenstor; tetradic四阶魔术方块: rubik's revenge方程: [数学] equation 三次方程 cubic equation; 高次方程 equation of higher degree; 线性方程 linear equation; 把方程式简化成 ... reduce the equation to ...; 物态方程 equation of state; 化学方程 chemical equation重力异常阶方差: degree variance of gravity anomaly广告作用四阶段: aida决策过程四阶段: four stagesofdecisionmaking四阶层评估模型: kirkpatrick's four-level model of evaluation; kirkpatrick’s four-level model of evaluation四阶对数比例尺: four cycle logarithmic scale四阶马尔柯夫链: fourth-order markov chain