启用/禁用多个文本框

代码：

<?php
include('conect.php');
$result = mysqli_query($conn,"SELECT * FROM `op` WHERE `type` = 2 ;");
   echo "<table class='table table-striped table-hover'id='datatables-example'>
      <tr>        
          <td class='pure-table'><b>Title 1</b></td>
          <td class='pure-table'><b>Title 2</b></td>
          <td class='pure-table'><b>Check 1</b></td>
          <td class='pure-table'><b>Title 3</b></td>
          <td class='pure-table'><b>VCheck 2</b></td>              
     </tr>";
 while($row = mysqli_fetch_array($result)) 
      {
        echo "<tbody data-link='row' class='rowlink'>
        <tr>
        <td>' . $row['Op'] . '</td>
        <td>  <input type='text' name='T2' class='form-control'>
        <td  style='text-align:center;'>  <input type='checkbox' name='C1' id='C1' >
        <td>  <input type='text' name='T3' id='T3' class='form-control' disabled >
        <td  style='text-align:center;'>  <input type='checkbox' name='C2'>
        </tr>
        </tbody>   
       }
        </table>";
        mysqli_close($conn);   
?>
<script language ="JavaScript">                                                      
document.getElementById('C1').onchange = function() {
  document.getElementById('T3').disabled = !this.checked;
};
</script>

我想启用/禁用由输入数据的行号生成的多个文本框。

第一行很好，但其他行不行。

我做错了什么？