\begin{table}%t5
\caption{\label{table:05}Coefficients of the 
         best-fit polynomials for the observed relations between 
         the emission-line flux ratios and the oxygen abundance,
         where $\log ~R = a_0 + a_1 x + a_2 x^2 + a_3 x^3$
         [$x \equiv$ log($Z$/$Z_\odot) \equiv 12+\log($O/H$)-8.69$].}
\small%\centering
\par
\begin{tabular}{l c c c c }
\hline\hline
Flux ratio (log~$R$) & 
$a_0$ &
$a_1$ &
$a_2$ &
$a_3$ \\
\hline 
log $R_{23}$ &
   +7.1806E--1 & --6.9548E--1 & --6.2220E--1 & --6.3169E--2 \\
log [$F$([N{\sc ii}]$\lambda6584$)/$F$(H$\alpha$)] &
  --6.8307E--1 &  +8.9881E--1 & --5.2302E--1 & --2.2040E--1 \\ 
log [$F$([O{\sc iii}]$\lambda$5007)/$F$([N{\sc ii}]$\lambda$6584)] &
   +3.2921E--1 & --2.2578E+0  & --4.1699E--2 &  +3.7941E--1 \\
log [$F$([N{\sc ii}]$\lambda$6584)/$F$([O{\sc ii}]$\lambda$3727)] &
  --7.9322E--1 &  +1.1399E+0  &  +7.8929E--1 &  +2.7101E--1 \\
log [$F$([N{\sc ii}]$\lambda$6584)/$F$([S{\sc ii}]$\lambda$6720)] &
  --2.5214E--1 &  +7.4100E--1 &  +5.8181E--1 &  +1.7963E--1 \\
log [$F$([O{\sc iii}]$\lambda$5007)/$F$([O{\sc ii}]$\lambda$3727)] &
  --3.0777E--1 & --1.1210E+0  & --1.4359E--1 & ---  \\
\hline
\end{tabular}
\end{table}