$\begin{matrix} C{{H}_{3}}\,\,\,\,\,\,\, \\ |\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\ {{H}_{3}}C-C-CH=C{{H}_{2}} \\ |\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\ C{{H}_{3}}\,\,\,\,\,\,\,\,\, \\ \end{matrix}$