+2y)dx+(2x+3(y)^2)dy在整个xoy平面内是某一函数+2y)dx+(2x+3(y)^2)dy的全微分，则+2y)dx+(2x+3(y)^2)dy（）A，+2y)dx+(2x+3(y)^2)dyB，+2y)dx+(2x+3(y)^2)dyC，+2y)dx+(2x+3(y)^2)dyD，+2y)dx+(2x+3(y)^2)dy