关于用jquery给<li>标签下的所有的第二个和第三个<span>标签赋值问题

可以这样：

 <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.1.min.js"></script>
<ul id="ul">
    <li>
        <a href="javascript:void(0)">
            <span>卖5</span>
            <span class="" id="mcjg5">--</span>
            <span id="mcs15">--</span>
        </a>
    </li>
    <li>
        <a href="javascript:void(0)">
            <span>卖4</span>
            <span class="" id="mcjg4">--</span>
            <span id="mcs14">--</span>
        </a>
    </li>
</ul>
<script>
    $('#ul li span:not(:first-child)').html('new value');
</script>