$(1)$ $\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,\,\,\,\,\,} \\ 
  | \,\,\,\\ 
  {2C{H_3} - CH - CHO} 
\end{array}$ $+$ $NaOH$ $\to $ $\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  |\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\ 
  {C{H_3} - CH - C{H_2}OH} 
\end{array}$ $+$ $\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  | \,\,\,\,\,\,\,\,\,\,\\ 
  {C{H_3} - CH - C{H_2}Na} 
\end{array}$ 

$(2)$ $\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}\,\,\,\,\,\,\,\,\,\,} \\ 
  |\,\,\,\,\,\,\, \\ 
  {C{H_3} - CH - CHO} 
\end{array} +  {H - \,\,\begin{array}{*{20}{c}}
  \,\,\,\,{C{H_3}} \\ 
  | \,\,\,\\ 
  {{C^\infty }} \\ 
  |\,\,\, \\ 
  \,\,\,{C{H_3}} 
\end{array} - CHO}$ $\to $ $\begin{array}{*{20}{c}}
 \,\,\,\,\,{C{H_3}\,\,\,\,\,\,\,OH\,\,\,\,\,\,\,\,C{H_3}} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,} \\ 
  {C{H_3} - CH - CH - C - CHO} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}$