\begin{table}%t6
 \caption{Chemical abundances of the knots.}
 \label{table4s}
%\centerline
{
 \begin{tabular}{lcccccccccccc}
   \hline\hline
    Knot           & C WHT & C INT& N WHT & N INT  &\#7 WHT&\#7 INT& \#1   & \#3    & \#8   &\#13   &\#14   &\#15 \\
    \hline
12+log O/H$^a$     & 8.57  & 8.53 & 8.23   & 8.24  & 8.55  & 8.53  & 8.50: & 8.52:  & 8.41  & 8.47  & 8.43  & 8.44  \\
12+log O/H$^b$     & 8.79  & 8.78 & 8.31   & 8.32  & 8.52  & 8.54  & 8.59  & 8.58   & 8.63  & 8.57  & 8.62  & 8.68  \\
(O$^{++}$+O$^+$)/O$^+$&1.55& 1.53  & 1.53  & 1.99  & 2.19  & 1.85  &\nodata&\nodata & 1.57  & 1.64  & 1.61  & 1.67  \\
12+log N/H         & 7.76  & 7.71  & 6.77  & 6.90  & 7.48  & 7.43  &\nodata&\nodata & 7.33  & 7.48  & 7.32  & 7.32  \\
$-$ log N$^+$/O$^+$& 0.81  & 0.83  & 1.46  & 1.34  & 1.08  & 1.10  &\nodata&\nodata & 1.08  & 0.99  & 1.11  & 1.00  \\
12+log Ne$^{++}$/H$^+$& 7.67& 7.60 & 7.53  & 7.42  & 7.56  & 7.79  &\nodata&\nodata &\nodata&\nodata&\nodata&\nodata\\
12+log S$^+$/H$^+$ & 6.54  & 6.50  & 6.24  & 6.07  & 6.31  & 6.34  &\nodata&\nodata & 6.38  & 6.44  & 6.33  & 6.45  \\
12+log S$^{++}$/H$^+$ & 6.42  &\nodata&\nodata&\nodata&\nodata&\nodata&\nodata&\nodata 
&\nodata&\nodata&\nodata&\nodata\\
12+log He$^+$/H$^+$$^c$&10.84 & 10.88 & 10.97 & 11.03 & 10.82 & 10.94 &\nodata&\nodata &\nodata&\nodata& 10.91 
&\nodata\\
 \hline
[O/H]/[O/H]$_{\odot}$$^d$&0.76&0.69&0.35& 0.35& 0.72  & 0.69  & 0.72: & 0.65:  & 0.60  & 0.71  & 0.55  & 0.56  \\
 \hline
 \end{tabular}}
\medskip
 $^a$ Determined using the empirical calibration of \citet{P01}.\\
 $^b$ Determined using the $[$N II$]$/H$\alpha$ ratio \citep{D02}.\\
 $^c$ Using only the He I $\lambda$5875 emission line.\\
 $^d$ Asuming 12+$\log$[O/H]$_\odot$ = 8.69$\pm0.05$ \citep{AP01}.
\end{table}