\begin{table}%t5 \caption{\label{tab_other}The radial gradients of N/H, Ne/H, S/H and Ar/H.} %\centering \par \begin{tabular}{lll} \hline\hline\noalign{\smallskip} 12 + log(X/H) &slope & central value \\ (1) &(2) &(3) \\ \hline N/H & --0.08 $\pm$ 0.03 & 7.53 $\pm$ 0.15 \\ Ne/H & --0.05 $\pm$ 0.04 & 7.71 $\pm$ 0.21 \\ S/H & --0.06 $\pm$ 0.02 & 6.41 $\pm$ 0.11 \\ Ar/H & --0.07 $\pm$ 0.03 & 6.98 $\pm$ 0.13 \\ \hline \end{tabular} \end{table}