1 $\begin{array}{*{20}{c}}
{R\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{R' - C - C{H_2}OH} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{R\,\,\,\,\,\,\,\,\,\,\,\,}
\end{array}$
2 $\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,R'} \\
{\,\,\,\,\,|} \\
{RC{H_2} - C - OH} \\
{\,\,\,\,|} \\
{\,\,\,\,\,R}
\end{array}$
3 $\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,R\,} \\
{\,\,\,\,\,\,\,|} \\
{R'C{H_2} - C - OH} \\
{\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,R}
\end{array}$
4 $\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,R\,} \\
{\,\,\,\,\,|} \\
{RC{H_2} - C - OH} \\
{\,\,\,\,|} \\
{\,\,\,\,\,R'}
\end{array}$