\begin{table}%t5
\caption {\label{tab_abund}Carbon, nitrogen and oxygen abundances and 3D corrections.  } 

%\centerline
 {\begin{tabular}{l cccc}
\hline \hline
\noalign{\smallskip}
Element      & [X/Fe]$_{\rm 1D}$ & [X/Fe]$_{\rm 3D}$ & 3D--1D  &  3D--$\left\langle{\rm 3D}\right\rangle$ \\
\hline
             & \multicolumn{4}{c}{SDSS J1349-0229}   \\
CH           & 2.82 & 2.09  & --0.73 & --0.37 \\
C$_2$        & 3.16 & 1.72  & --1.44 & --0.82 \\
C {\sc i} NLTE   & 2.42 & 2.51 & 0.08   & --0.04 \\
NH           & 1.60 & 0.67  & --0.93 & --0.34 \\
OH           & 1.88 & 1.70  & --0.18 & --0.06 \\
O {\sc i} NLTE   & 1.63 & 1.69  & 0.06   & --0.04 \\
\hline
             & \multicolumn{4}{c}{SDSS J0912+0216}  \\
CH           & 2.17 & 1.67  & --0.50 & --0.20 \\
C {\sc i} NLTE   & 1.38 &  1.44 &  0.06  & --0.03 \\
NH           & 1.75 & 1.07  & --0.67 & --0.30 \\
\hline
             &  \multicolumn{4}{c}{SDSS J1036+1212}   \\
CH           & 1.47 & 0.96  & --0.51 & --0.11 \\
NH           &  1.29 & 0.51  & --0.78 & --0.08 \\
\hline
\end{tabular}}
\vspace*{-1.5mm}
\tablefoot{Abundances
  are expressed with respect to the solar abundances of log~($\epsilon$)~=~8.50,
  7.86, and 8.76 for carbon, nitrogen and oxygen,\protect respectively.}
\label{tab_cn}
\end{table}