(12)KA2\left(\frac{1}{2}\right) \mathrm{KA}^{2}(21)KA2
(12)K2 A\left(\frac{1}{2}\right) \mathrm{K}^{2} \mathrm{~A}(21)K2 A
(12)KX2\left(\frac{1}{2}\right) \mathrm{KX}^{2}(21)KX2
−KX2-KX^2−KX2