a29.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- align="center/right/left"   -->
    <table border="1" align="center" bgcolor="yellow">
        <tr height="50px">
            <td>1</td>
            <td>2</td>
            <td>3</td>
            <td>4</td>
        </tr>
        <!-- <tr width="50px"> width not allowed in tr -->
        <tr>
            <td>5</td>
            <td>6</td>
            <td>7</td>
            <td>8</td>
        </tr>
        <tr>
            <td>9</td>
            <td>10</td>
            <td>11</td>
            <td>12</td>
        </tr>
    </table>
</body>
</html>