 ![a) The plot of $\omega_{\phi}$ in terms of $z$ and for some values of the parameters $\lambda$ and $n$. There is not any phantom behavior in these cases. b) The plot of $\omega_{\phi}$ for the redshift $z=0.00$. Even though in a small region $\omega_{\phi}$ takes negative values, it does not however cross the PDL. ](fig0b.eps "fig:"){width="0.00\linewidth"}  ![The plot of $\omega_{\phi}(z)$ for (a) Starobinsky's and (b) Hu-Sawicki's models. As the figures indicate, there is a phantom-like behavior in the latter.](fig0a.eps "fig:"){width="0.00\linewidth"} ![The plot of $\omega_{\phi}(z)$ for (a) Starobinsky's and (b) Hu-Sawicki's models. As the figures indicate, there is a phantom-like behavior in the latter.](fig0b.eps "fig:"){width="0.00\linewidth"}  ![The plot of $\omega_{\phi}$ in the redshift $z=0.00$ for (a) Starobinsky's and (b) Hu-Sawicki's models. As the figures show the PDL can be crossed in the latter in a small region of the parameters space.](fig0a.eps "fig:"){width="0.00\linewidth"} ![The plot of $\omega_{\phi}$ in the redshift $z=0.00$ for (a) Starobinsky's and (b) Hu-Sawicki's models. As the figures show the PDL can be crossed in the latter in a small region of the parameters space.](fig0