\begin{table}%t3 %\centering \par \caption{\label{tab3}Relative line intensities and observational parameters for SNRs spectroscopically observed in M~74.} \small \begin{tabular}{c c c c} \hline\hline Line & SNR2 & SNR3 & SNR5 \\ \hline H$\beta$($\lambda$4861)& 100 & 100 & 100\\ OIII($\lambda$4959)& 3 & 60 & 50\\ OIII($\lambda$5007)& 27 & 122 & 160\\ NII($\lambda$5200) & -- & 3 & --\\ He($\lambda$5876) & 13 & 33 & 9 \\ OI($\lambda$6300) & 17 & 21& 32\\ OI($\lambda$6364) & 14 &--& 7\\ NII($\lambda$6548) & 30 & 154& 56\\ H$\alpha$($\lambda$6563)& 288 & 589 & 335\\ NII($\lambda$6583)& 48 & 281 & 85\\ SII($\lambda$6716) & 92 & 297& 122\\ SII($\lambda$6731) & 41 & 239 & 73\\ \hline $E_{(B-V)}$& 0.07 & 0.06 & 0.06\\ I(H$\alpha$ )& 6.0E-15 erg cm$^{-2}$ s$^{-1}$& 2.9E-15 erg cm$^{-2}$ s$^{-1}$ & 2.8E-15 erg cm$^{-2}$ s$^{-1}$ \\ $[$SII$]$/H$\alpha$ & 0.46 & 0.91 & 0.58\\ \hline \end{tabular} \end{table}