$\begin{array}{*{20}{c}}{CHO}\\|\\{HCOH}\\|\\{HOCH}\\|\\{HCOH}\\|\\{C{H_2}OH}\\I\end{array}$ $\begin{array}{*{20}{c}}{CHO}\\|\\{HCOH}\\|\\{HCOH}\\|\\{HOCH}\\|\\{C{H_2}OH}\\{II}\end{array}$ $\begin{array}{*{20}{c}}{CHO}\\|\\{HCOH}\\|\\{HCOH}\\|\\{HCOH}\\|\\{C{H_2}OH}\\{III}\end{array}$
$(i)$ Diastereomers $(ii)$ Geometrical isomers
$(iii)$ Epimers $(iv)$ Anomers
$(v)$ Enantiomers