checkbox传值的问题，懂的请进来看看，谢谢了。

<tr>
    <td width="7%" align="left" valign="middle"><input type="checkbox" name="gift[]" id="checkbox" onClick="return checknum()" value="Glutathione Resin Kit (10ml)" /></td>
    <td width="93%" align="left" valign="middle">Glutathione Resin Kit (10ml)</td>
  </tr>
  <tr>
    <td align="left" valign="middle"><input type="checkbox" name="gift[]" value="Protein G Resin Kit (5 ml)" id="checkbox2" onClick="return checknum()" /></td>
    <td align="left" valign="middle">Protein G Resin Kit (5 ml)</td>
  </tr>
  <tr>
    <td align="left" valign="middle"><input type="checkbox" name="gift[]" id="checkbox3" onClick="return checknum()" value="Protein A Resin Kit (5 ml)"/></td>
    <td align="left" valign="middle">Protein A Resin Kit (5 ml)</td>
  </tr>
  <tr>
    <td align="left" valign="middle"><input type="checkbox" name="gift[]" id="checkbox4" onClick="return checknum()" value="ToxinEraser Endotoxin Removal Kit (5 assay)"/></td>
    <td align="left" valign="middle">ToxinEraser Endotoxin Removal Kit (5 assay)</td>
  </tr>
  <tr>
    <td align="left" valign="middle"><input type="checkbox" name="gift[]" id="checkbox5" onClick="return checknum()" value="ToxinSensor Gel Clot Endotoxin Assay Kit (40 rxns)"/></td>
    <td align="left" valign="middle">ToxinSensor Gel Clot Endotoxin Assay Kit (40 rxns)</td>
  </tr>
  <tr>
    <td align="left" valign="middle"><input type="checkbox" name="gift[]" id="checkbox6" onClick="return checknum()" value="ToxinSensor Chromogenic LAL Endotoxin Assay Kit(16 rxns)"/></td>
    <td align="left" valign="middle">ToxinSensor Chromogenic LAL Endotoxin  Assay Kit(16 rxns)</td>
  </tr>

      $str='';
      $gift =$_POST['gift'];
    foreach($_POST['gift'] as $g)
    {
        $str.=$g;
    }