$(a)$ $\underset{(no\,\,\alpha -H)}{\mathop{\begin{matrix}
   \,\,\,\,\,\,\,\,\,\,\,O  \\
   \,\,\,\,\,\,\,\,\,\,\,||  \\
   C{{l}_{3}}\overset{\alpha }{\mathop{C}}\,CH  \\
\end{matrix}}}\,$     $(b)$ $\underset{(\alpha -H)}{\mathop{{{C}_{6}}{{H}_{5}}\overset{\alpha }{\mathop{C}}\,{{H}_{2}}CHO}}\,$

$(c)$ $\underset{(\alpha -H)}{\mathop{{{C}_{4}}{{H}_{9}}\overset{\alpha }{\mathop{C}}\,{{H}_{2}}CHO}}\,$       $(d)$  $CH_3NO_2$