求翻译：设置中间变量，并引入空间及其范数，导出此二阶椭圆问题的混合模型。然后，应用最低阶的混合元，我们构造网格上单元和边的基函数，接着采用方法，将此模型问题转化为一个线性代数方程组，从而转化为求解方程组的系数。最后，通过我们可以得到近似解与真解的误差估计以及收敛阶，从而验证了应用最低阶元的混合有限元方法的正确性与准确性。是什么意思？

Set of intermediate variables, and the introduction of space and its norm, and to export the hybrid model of second order elliptic problem. Then, the application of the lowest order mixed finite element, we construct the grid unit and the edge of the base function, and then using the method, this mo

Sets the intermediate variables, and to introduce space and its norms, and the export of a 2nd-order elliptic problems of the hybrid model. And then, the application of the minimum order $mixed, we construct a grid on the base unit and function, followed by method, this model will be a problem into

Establishes the middle variable, and introduces the space and the norm, derives this two step elliptic problem the mix model.Then,%

Set the variable in the Middle, and the introduction of space and its norm, export the hybrid model of second order elliptic problem. And then, applying mixed finite element of lowest-order, we constructed on a grid basis function of the unit and, then, the model problem into a linear algebraic grou