\begin{table}%t3
  \caption{\label{sk}Normalized velocity difference.}
\small      %\centering
\par
\begin{tabular}{c c}         
\hline\hline  \noalign{\smallskip}                
Line & $\Delta V_{{\rm be}}$ \\      
\hline                         
   HCN$(J=4\rightarrow3)$              & --1.1  \\    
   HCO$^{+}(J=4\rightarrow3)$          &  --1.2 \\    
   CS$(J=7\rightarrow6)$               & --0.1  \\
\hline                                    
\end{tabular}
\tablefoot{The asymmetry of line profiles is presented by
    the calculation of $\Delta V_{{\rm be}}$, as shown in Eq.~(\ref{dv}),
    where the optically thin
    species correspond to H$^{13}$CO$^{+}$ for HCO$^{+}$ and 
    H$^{13}$CN for HCN and CS. The values used to compute the blue excess
    are taken from Gaussian fits to the corresponding spectra.
    }               
\end{table}