写了个可拖拽的div，为啥点击内部的select，div会往下跳？

    <div id="tzg1" class="tzgBox" onclick="none">
        <table class="tbLast2">
            <thead>
                <tr>
                    <th colspan="2"><a class="uploadimg" onclick="ImgBrow.show('../images/housePic.png');"></a>亚信小谷围-1期-1栋 第一单元</th>
                </tr>
            </thead>
            <tbody>
                <tr class="odd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px display:none">
                            <option>01</option>
                             <option>02</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
                <tr class="edd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
            </tbody>
        </table>
    </div>
    <div id="tzg2" class="tzgBox">
        <table class="tbLast2">
            <thead>
                <tr>
                    <th colspan="2"><a class="uploadimg1"></a>亚信小谷围-1期-1栋 第二单元</th>
                </tr>
            </thead>
            <tbody>
                <tr class="odd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
                <tr class="edd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
            </tbody>
        </table>
    </div>
    <div id="tzg3" class="tzgBox">
        <table class="tbLast2">
            <thead>
                <tr>
                    <th colspan="2"><a class="uploadimg1"></a>亚信小谷围-1期-1栋 第三单元</th>
                </tr>
            </thead>
            <tbody>
                <tr class="odd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
                <tr class="edd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
            </tbody>
        </table>
    </div>
    <div id="tzg4" class="tzgBox">
        <table class="tbLast2">
            <thead>
                <tr>
                    <th colspan="2">  <a class="uploadimg1"></a>亚信小谷围-1期-1栋 第四单元</th>
                </tr>
            </thead>
            <tbody>
                <tr class="odd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
                <tr class="edd">
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                    <td class="dataTdNew dragtd">
                        <select style="width:58px">
                            <option>01</option>
                        </select>
                        <div><em> 均套面积:</em>
                            <i class="i1">91.93</i>
                        </div>
                        <div><em> 均&nbsp;&nbsp;价:</em>
                            <i>20,675.61</i>
                        </div>
                        <div><em> 金&nbsp;&nbsp;额:</em>
                            <i>68,921,981.92</i>
                        </div>
                    </td>
                </tr>
            </tbody>
        </table>
    </div>
</div>