$(1)$ $C{H_3} - \mathop {CH}\limits^| - {C_2}{H_5}$
$(2)$ $C{H_2} = \,\mathop C\limits^| \, - \,\,C{H_3}$
$(3)$ $ CH_2 = CH -$
$(4)$ $(CH_3)_2 CH -$
$(II)\,\,\,{{H}_{2}}C=CH-C{{H}_{2}}-\overset{+}{\mathop{C}}\,H-C{{H}_{3}}$
$(III)\,\,\,\begin{matrix}
\,\,\,\,\,C{{H}_{3}}\, \\
|\, \\
{{H}_{3}}C-C-\overset{+}{\mathop{C}}\,{{H}_{2}} \\
|\, \\
\,\,\,C{{H}_{3}} \\
\end{matrix}$