1 $\begin{array}{*{20}{c}}
{\begin{array}{*{20}{c}}
{C{H_3}}\,\,\, \\
{|\,\,\,\,\,\,\,\,\,\,\,}
\end{array}\,\,} \\
{{H_3}C - C - O - C{H_3}} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3}\,\,\,\,\,}
\end{array}$
2 \(CH_3-CH_2-CH_2-CH_2-O-CH_3\)
3 $\begin{array}{*{20}{c}}
{{H_3}C - CH - C{H_2} - C{H_3}} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{O - C{H_3}\,\,\,\,\,\,\,\,}
\end{array}$
4 $\begin{matrix}
{{H}_{3}}C-C=CH-C{{H}_{3}} \\
\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
OC{{H}_{3}}\,\,\, \,\,\,\,\,\, \\
\end{matrix}$