About plane strain and plane stress formulations, which of the following statements are correct descriptions?
选项：

A:One formulation can be converted to another by the simultaneous replacements of Young’s modulus and Poisson’s ratio.;
B:With the help of Kolosov’s constant, they be expressed with an identical form.;
C:The governing equations of two formulations differ only by elastic constants.;
D:The method of Airy stress function is valid for both formulations.