\begin{table}%t3
%\setlength{\tabcolsep}{1pt}
\caption{The spectral indexes of the VLBI components.\label{tab:3}}   
%\centerline
 {\begin{tabular}{ccccccc}
\hline\hline
 &\multicolumn{6}{c}{Component}\\ \cline{2-7}
epoch&$k$& $b$& $d$& $e$& $f$&$g$ \\\hline
\noalign{\smallskip}
 2001.20&
0.067&--1.28$\pm^{0.28}_{0.32}$&--0.44~$\pm$~0.09&--0.52&--0.11&--0.54\\
2001.48&0.22&--$4.52\pm({>}0.32)$&--0.47~$\pm$~0.09&--0.28&0&$-2.27\pm({>}0.47)$\\
2001.86&0.052&&--0.51&--0.11&--0.48&--0.19\\
2002.11&0.05&&--0.57&--0.24&--0.23&--0.54\\
2002.14&0.21&&--0.56&--0.15&--0.32&--0.11\\
2002.45&0.03&&--0.41&--0.12&--0.17&--0.30\\\hline
\end{tabular}}
\par
\smallskip
\hspace{35mm}Note: The errors, if not shown in the table, are all 0.16.
\end{table}