\begin{table}%t4
\caption{\label{table:04}Means and RMSs of emission-line flux ratios of 
         the galaxies in sample~C$^{{a}}$.}
\small%\centerline
{
\begin{tabular}{l c c c c c c}
\hline\hline
\noalign{\smallskip}
Oxygen abundance                                                    & 
log$~R_{23}$                                                         &
log$\frac{F([{\rm NII}]\lambda6584) }{F({\rm H}\alpha)}$            &
log$\frac{F([{\rm OIII}]\lambda5007)}{F([{\rm NII}]\lambda6584)}$   &
log$\frac{F([{\rm NII}]\lambda6584) }{F([{\rm OII}]\lambda3727)}$   &
log$\frac{F([{\rm NII}]\lambda6584) }{F([{\rm SII}]\lambda6720)}$   &
log$\frac{F([{\rm OIII}]\lambda5007)}{F([{\rm OII}]\lambda3727)}$  \\
\noalign{\smallskip}
\hline 
\noalign{\smallskip}
$8.15 \leq  12 +  {\rm log (O/H)}  <  8.25$ & 
     0.835  & --1.138 &  1.102  & --1.196 & --0.532 & --0.089 \\ 
  & (0.043) & (0.081) & (0.171) & (0.077) & (0.042) & (0.140) \\
%\noalign{\smallskip}
$8.25 \leq  12 +  {\rm log (O/H)}  <  8.35$ & 
     0.825  & --1.031 &  0.936  & --1.113 & --0.480 & --0.191 \\ 
  & (0.053) & (0.077) & (0.187) & (0.082) & (0.038) & (0.170) \\
%\noalign{\smallskip}
$8.35 \leq  12 +  {\rm log (O/H)}  <  8.45$ & 
     0.817  & --0.934 &  0.768  & --1.056 & --0.444 & --0.283 \\ 
  & (0.060) & (0.088) & (0.199) & (0.084) & (0.033) & (0.174) \\
\noalign{\smallskip}
$8.45 \leq  12 +  {\rm log (O/H)}  <  8.55$ & 
     0.805  & --0.851 &  0.644  & --0.985 & --0.397 & --0.309 \\ 
  & (0.061) & (0.119) & (0.237) & (0.102) & (0.034) & (0.184) \\
%\noalign{\smallskip}
$8.55 \leq  12 +  {\rm log (O/H)}  <  8.65$ & 
     0.772  & --0.812 &  0.572  & --0.910 & --0.334 & --0.329 \\ 
  & (0.052) & (0.101) & (0.216) & (0.091) & (0.047) & (0.170) \\
%\noalign{\smallskip}
$8.65 \leq  12 +  {\rm log (O/H)}  <  8.75$ & 
     0.711  & --0.689 &  0.300  & --0.780 & --0.238 & --0.466 \\ 
  & (0.052) & (0.083) & (0.188) & (0.084) & (0.051) & (0.147) \\
%\noalign{\smallskip}
$8.75 \leq  12 +  {\rm log (O/H)}  <  8.85$ & 
     0.637  & --0.596 &  0.060  & --0.642 & --0.146 & --0.573 \\ 
  & (0.052) & (0.068) & (0.160) & (0.075) & (0.051) & (0.135) \\
%\noalign{\smallskip}
$8.85 \leq  12 +  {\rm log (O/H)}  <  8.95$ & 
     0.559  & --0.516 & --0.159 & --0.508 & --0.053 & --0.663 \\ 
  & (0.058) & (0.058) & (0.139) & (0.077) & (0.052) & (0.120) \\
%\noalign{\smallskip}
$8.95 \leq  12 +  {\rm log (O/H)}  <  9.05$ & 
     0.454  & --0.447 & --0.383 & --0.345 &  0.054  & --0.731 \\ 
  & (0.071) & (0.056) & (0.123) & (0.088) & (0.057) & (0.108) \\
%\noalign{\smallskip}
$9.05 \leq  12 +  {\rm log (O/H)}  <  9.15$ & 
     0.324  & --0.415 & --0.591 & --0.174 &  0.171  & --0.777 \\
  & (0.084) & (0.052) & (0.126) & (0.100) & (0.057) & (0.101) \\
%\noalign{\smallskip}
$9.15 \leq  12 +  {\rm log (O/H)}  <  9.25$ & 
     0.168  & --0.398 & --0.706 &  0.016  &  0.286  & --0.758 \\
  & (0.074) & (0.056) & (0.192) & (0.085) & (0.044) & (0.118) \\
%\noalign{\smallskip}
\hline
\end{tabular}}
\smallskip
$^{{a}}$
  Mean and RMS  of each emission-line flux ratio are given
  in the upper and lower rows. RMSs are given in parenthesis.
\end{table}