Since A and B represent the difference of packing status between gas and liquid, the more significant value indicates that the packing is tighter in liquid, provided that the packing status in gas is entirely random. Hence, as the molecular motion slows down at a lower temperature, it is rational that the packing becomes tight, thereby giving the more significant values of A and B. This result indicates that A and B vary along with the temperature variation. The linear regression over the whole range of temperature from M.P. to Tc gives the averaged A and B values. D 2 =1 is just a signal of tiny variation. 4) The same configuration exhibits a different symmetry according to A and D 2 . For example, the configuration of both NH3 and NF3 is a tetrahedron with a vertex occupied by an unbonded p orbital. However, the averaged A and D 2 of the two molecules are quite different. D 2 =0.9998 exhibits that NH3 is close to a symmetric molecule, while D 2 =0.999 indicates that the symmetry of NF3 is inferior. However, an inverse conclusion is drawn from the A values (NH3: A=4.8459; NF3: A=4.1011). Therefore, we have to utilize the interval value. In the 85-97.5K interval, the linear regression of NF3 gives A=5.7103. Comprehensively, it is concluded that the symmetry of NH3 is superior to that of NF3. Fortunately, the assessment is consistent in the pairs of H2O and H2S and CH4 and CF4. For H2O, A=5.3322, D 2 = 0.9998; H2S: A=3.6898, D 2 = 0.9999, whilst for CH4, A=2.9519, D 2 =1; CF4: A=4.0262, D 2 = 0.9997. Accordingly, the symmetry of H2S and CH4 is better than that of their counterparts. It indicates that the unbonded p orbital, e.g., 2p of the Fluorine atom, and its size, e.g., 3p of the Sulfur atom, impact the molecule's symmetry. This result suggests that the symmetry of the molecular orbital, rather than the conventional mass symmetry , is proper to be a criterion for accessing molecule symmetry. However, the sign symmetry of the molecular orbital in Woodward and Hoffmann's rule should be excluded. As a result, set D 2 → 1 as possible, A is solid for assessing the molecule's symmetry, though, in most cases, the averaged A is reliable enough.