sensitivity of symmetry energy at the time of maximum compression and at freeze-out time, we display the incident energy and isospin asymmetry dependencies of the single neutron-to-proton ratio at different times in Figs. \[fig:4\], \[fig:5\] and \[fig:6\]. The left and right panels are at the time of maximum compression and freeze-out time, respectively. In Fig. \[fig:4\], the ratios from free nucleons and LCPs are displayed in the top and bottom panels. The many interesting facts are revealed in the figure. The incident energy dependencies of the ratios are found to be highly sensitive to symmetry energy for the two different times. As we know, the relative strength of symmetry energy is opposite at sub- and supra-saturation densities with $\gamma_i=0.5$ and $\gamma_i=1.5$. In the range of 50-150 MeV/nucleon, only the low density part up to about 1.1$\rho_0$ contributes. Therefore, in the low-energy region, for free nucleons, we can see the high ratio with the soft symmetry energy at both the times under consideration. At and above 200 MeV/nucleon, a broad range of densities up to 1.8$\rho_0$ is involved. Of course, at about 200 MeV/nucleon and above, for the behavior of the high-density symmetry energy, there is a combined effect for particles 