\begin{center}
  \begin{tabular}{|c c c c c c c c|}
    \hline
    A & B & C & D & E & F & G & H \\ [0.5ex]
    \hline
    $a$ & $b$ & $c$ & $d$ & ${e}_1$ & ${f}_1$ & $g$ & ${h}_1$ \\
    ${a}_2$ & $b$ & ${c}_2$ & ${d}_2$ & $e$ & ${f}_2$ & ${g}_2$ & $h$ \\
    $a$ & $b$ & ${c}_3$ & ${d}_3$ & ${e}_3$ & $f$ & $g$ & $h$ \\
    \hline
  \end{tabular}\\
  $\downarrow$\\
  \begin{tabular}{|c c c c c c c c|}
    \hline
    A & B & C & D & E & F & G & H \\ [0.5ex]
    \hline
    $a$ & $b$ & $c$ & $d$ & ${e}_1$ & ${f}_1$ & $g$ & ${h}_1$ \\
    ${a}_2$ & $b$ & ${c}_2$ & ${d}_2$ & $e$ & ${f}_2$ & ${g}_2$ & $h$ \\
    $a$ & $b$ & $c$ & $d$ & ${e}_3$ & $f$ & $g$ & $h$ \\
    \hline
  \end{tabular}\\
  $\downarrow$\\
  \begin{tabular}{|c c c c c c c c|}
    \hline
    A & B & C & D & E & F & G & H \\ [0.5ex]
    \hline
    $a$ & $b$ & $c$ & $d$ & ${e}_1$ & ${f}_1$ & $g$ & $h$ \\
    ${a}_2$ & $b$ & ${c}_2$ & ${d}_2$ & $e$ & ${f}_2$ & ${g}_2$ & $h$ \\
    $a$ & $b$ & $c$ & $d$ & ${e}_3$ & $f$ & $g$ & $h$ \\
    \hline
  \end{tabular}\\
  $\downarrow$\\
  \begin{tabular}{|c c c c c c c c|}
    \hline
    A & B & C & D & E & F & G & H \\ [0.5ex]
    \hline
    $a$ & $b$ & $c$ & $d$ & $e$ & ${f}_1$ & $g$ & $h$ \\
    ${a}_2$ & $b$ & ${c}_2$ & $d$ & $e$ & ${f}_2$ & ${g}_2$ & $h$ \\
    $a$ & $b$ & $c$ & $d$ & $e$ & $f$ & $g$ & $h$ \\
    \hline
  \end{tabular}
\end{center}