$\,\text{C}{{\text{H}}_{\text{3}}}\text{Br }\xrightarrow{\text{KCN}}A\xrightarrow{{{H}_{3}}O}B\xrightarrow{LiAl{{H}_{4}}}C$
$(1)$ $C{H_3}C{H_2}C{H_2}Cl + $ $\begin{array}{*{20}{c}}
{\,\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,C{H_3}} \\
{\,\,\,|}
\end{array}} \\
{C{H_3} - C - {O^ - }} \\
{\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,C{H_3}}
\end{array}$ $(2)$ $C{H_3}C{H_2}C{H_2}I + $$\begin{array}{*{20}{c}}
{\,\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,C{H_3}} \\
{\,\,\,|}
\end{array}} \\
{C{H_3} - C - {O^ - }} \\
{\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,C{H_3}}
\end{array}$
$(3)$ $\begin{array}{*{20}{c}}
{{H_3}C - CH - C{H_3}} \\
{|\,\,\,\,} \\
{Br\,\,\,}
\end{array}$ $+CH_3O^-$ $(4)$ $\begin{array}{*{20}{c}}
{{H_3}C - CH - C{H_3}} \\
{|\,\,\,\,} \\
{Br\,\,\,}
\end{array}$ $+CH_3S^-$
$(a)$ $CH_3CH_2CH_2CH_2Br$
$(b)$ $\begin{matrix}
\begin{matrix}
\,\,\,\,\,\,C{{H}_{3}} \\
| \\
\end{matrix} \\
{{H}_{3}}C-C-C{{H}_{3}} \\
| \\
\,\,Br \\
\end{matrix}$
$(c)$