1 $\begin{array}{*{20}{c}}
{C{H_3} - C{H_2} - CH = C - C{H_2} - C{H_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_2} - C{H_3}}
\end{array}$
2 $\begin{array}{*{20}{c}}
{C{H_3} - CH = C - C{H_2} - C{H_3}} \\
{\,|\,\,\,\,\,\,} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_2} - C{H_3}}
\end{array}$
3 $\begin{array}{*{20}{c}}
{C{H_3} - C{H_2} - C - C{H_2} - C{H_3}} \\
{\,||} \\
{C{H_3} - C - C{H_3}}
\end{array}$
4 $\begin{array}{*{20}{c}}
{C{H_3} - CH = CH - CH - C{H_2} - C{H_2} - C{H_3}} \\
{\,\,|\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3\,\,\,}}
\end{array}$