contours consist of points where the likelihood equals $e^{-2.31/2}$, $e^{-6.18/2}$, and $e^{-11.83/2}$ of the maximum value of the likelihood, respectively. Fig.7 shows our main results, the contours of $1\sigma$, $2\sigma$, and $3\sigma$ confidence levels in the $w_X-\eta$ plane. The 1 $\sigma$ fit values for the model parameters are: $w_X=-0.98^{+0.15}_{-0.20}$ and $\eta=1.06^{+0.20}_{-0.16}$, and the minimum value of $\chi^2$ in the four dimensional parameter space is: $\chi_{\rm
min}^2=167.29$. We see clearly that the combined analysis of SNe Ia, CMB, and LSS data provides a fairly tight constraint on the NGCG model. It is remarkable that the best fit happens at the vicinity of the cosmological constant, even though $w_X$ is slightly larger than $-1$ and $\eta$ is mildly larger than 1 (i.e. $\alpha$ slightly larger than 0). This means that within the framework of the NGCG model the real form of dark energy at the maximum probability is the near cosmological constant according to the joint analysis of SNe+CMB+LSS data. However, the analysis results still accommodate the existence likelihood of the “X-matter” and the interaction between dark energy and dark matter. In 1 $\sigma$ range, $w_X\in (-1.18, -0.83)$ and $\alpha\in (-0.1, 0.26)$. This implies that the probabilities of that dark energy behaves 