<style>
    table {
        border: 1px solid black;
        border-collapse: collapse;
        border-spacing: 0px;
    }

    td {
        padding: 10px;
        border: 1px solid black;
    }
</style>

<table>
    <tr>
        <td>0</td>
        <td rowspan="2">A</td>
        <td rowspan="3">X</td>
    </tr>
    <tr>
        <td>1</td>
    </tr>
    <tr>
        <td>2</td>
        <td rowspan="2">B</td>
    </tr>
    <tr>
        <td>3</td>
        <td>C</td>
    </tr>
</table>