$\begin{array}{*{20}{c}} {O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ {||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ {C{H_3} - C{H_2} - C - C{H_2} - C{H_2} - C{H_3}} \end{array}$
Total $= 4$ enol fonns