${ }^{-} \mathrm{OH}, \mathrm{R} \overline{\mathrm{O}}, \mathrm{CH}_3 \mathrm{CO} \overline{\mathrm{O}}, \mathrm{C} \overline{1}$
$1.\,\,\,\begin{array}{*{20}{c}}
{C{H_3} - C - {O^ - }} \\
{\,\,\,||} \\
{\,\,\,O}
\end{array}$ $2.\,\,CH_3O^-$ $3.\,\,CN^-$

$(A)$ $AgCN / KCN$
$(B)$ $RCOOAg / RCOOK$
$(C)$ $AgNO _{2} / KNO _{2}$
$(D)$ $AgI / KI$

$1.$ $HCHO$
$2.$ $ CH_3COCH_3$
$3.$ $PhCOCH_3$
$4.$ $PhCOPh$