$H_2C = C = CH - CH = O$
$sp^3$ - $sp^2$ - $sp$
$C{H_3}\, - \,\,C{H_2}\, - \,\,C{H_2}\, - \,\,\mathop C\limits_{\mathop {||}\limits_{OHC\,\, - \,\,C\,\, - \,\,C{H_2}\, - \,\,C{H_3}} } \,\, - \,\,COOH$