\begin{table}%t7
\caption{Observed and modeled line emissivity ratios for Henize 2-10 and NGC 253 using PDR models.}\label{tab:pdr}
%\begin{center}
\par
\begin{tabular}{c|cc}
\hline
\hline
 $E$ & NGC~253 & Henize~2-10 \\
(erg~cm$^{-2}$~s$^{-1}$~sr$^{-1}$)& observations & observations\\
\hline
$\frac{^{12}{\rm CO}(3-2)}{^{12}{\rm CO}(6-5)}$ & $0.19\pm 0.076^{*}$ & $0.22\pm 0.083^{*}$\\
%\hline
  $\frac{^{12}{\rm CO}(3-2)}{^{12}{\rm CO}(7-6)}$ & $0.27\pm 0.11^{*}$ & $0.16\pm 0.064^{*}$\\
%\hline
 $\frac{^{12}{\rm CO}(6-5)}{^{12}{\rm CO}(7-6)}$ & $1.38\pm 0.56^{*}$ & $0.74\pm 0.29^{*}$\\
%\hline
\hline
 $\frac{^{12}{\rm CO}(1-0)}{^{13}{\rm CO}(1-0)}$ & $12.73\pm 2.5^{*}$ & $16.82\pm 6.2^{*}$\\
%\hline
 $\frac{^{12}CO(2-1)}{^{13}CO(2-1)}$ & $14.44\pm 3.4^{*}$ & $22.22\pm 6.1^{*}$\\
%\hline
 $\frac{^{12}{\rm CO}(3-2)}{^{13}{\rm CO}(3-2)}$ & $10.61\pm 3.6^{*}$ & $10.21\pm 4.7^{*}$\\
%\hline
\hline
& Model & Model\\
\hline
$\frac{^{12}{\rm CO}(3-2)}{^{12}{\rm CO}(6-5)}$ & 0.26 & 0.18\\
%\hline
  $\frac{^{12}{\rm CO}(3-2)}{^{12}{\rm CO}(7-6)}$ & 0.34 & 0.15\\
%\hline
 $\frac{^{12}{\rm CO}(6-5)}{^{12}{\rm CO}(7-6)}$ & 1.32 & 0.86\\
%\hline
\hline
 $\frac{^{12}{\rm CO}(1-0)}{^{13}{\rm CO}(1-0)}$ & 15.42 & 15.07\\
%\hline
 $\frac{^{12}{\rm CO}(2-1)}{^{13}{\rm CO}(2-1)}$ & 9.72 & 8.02\\
%\hline
 $\frac{^{12}{\rm CO}(3-2)}{^{13}{\rm CO}(3-2)}$ &  7.92 & 6.27\\
\hline
 \end{tabular}
%\end{center}
\par
$^{*}$~Ratio derived from observations marked with asterisks in Tables~\ref{tab:obs1} and~\ref{tab:obs2}.\\
\end{table}