$\begin{matrix}
\overset{\Theta }{\mathop{\overset{\centerdot \,\centerdot }{\mathop{C}}\,}}\,{{H}_{2}}-C-C{{H}_{3}} \\
|| \\
O \\
\end{matrix}$ અને $\begin{matrix}
C{{H}_{2}}=C-C{{H}_{3}} \\
| \\
:\underset{\Theta }{\mathop{\underset{\centerdot \,\centerdot }{\mathop{O}}\,}}\,: \\
\end{matrix}$