我有这样的下拉列表
但必须显示单个下拉列表并添加其他下拉列表单击其他时间。这应该怎么做???像这样
这是 ASP.NET 代码
<table width="100%" border="0">
<tr>
<td>
<asp:DropDownList class="chzn-select validate[required]" ID="ddlconvenient1" runat="server">
</asp:DropDownList>
</td>
<td>
<div class="wrapper">
<div class="checkboxes">
<asp:CheckBoxList ID="ChkDay1" CssClass="chzn-choices " runat="server" RepeatDirection="Horizontal">
</asp:CheckBoxList>
</div>
</div>
</td>
<td><button id="btnAdd" type="button" onclick="addRow(this)">Add</button></td>
</tr>
<tr id="tr1" style=" display:none;">
<td>
<asp:DropDownList ID="ddlconvenient2" CssClass="chzn-select" runat="server">
</asp:DropDownList>
</td>
<td>
<div class="wrapper">
<div class="checkboxes">
<asp:CheckBoxList ID="ChkDay2" runat="server" RepeatDirection="Horizontal">
</asp:CheckBoxList>
</div></div>
</td>
</tr>
<tr id="tr2" style=" display:none;">
<td>
<asp:DropDownList ID="ddlconvenient3" CssClass="chzn-select" runat="server">
</asp:DropDownList>
</td>
<td>
<div class="wrapper">
<div class="checkboxes">
<asp:CheckBoxList ID="ChkDay3" runat="server" RepeatDirection="Horizontal">
</asp:CheckBoxList>
</div>
</div>
</td>
</tr>
<tr id="tr3" style=" display:none;">
<td>
<asp:DropDownList ID="ddlconvenient4" CssClass="chzn-select" runat="server">
</asp:DropDownList>
</td>
<td>
<div class="wrapper">
<div class="checkboxes">
<asp:CheckBoxList ID="ChkDay4" runat="server" RepeatDirection="Horizontal">
</asp:CheckBoxList>
</div></div>
</td>
</tr>
</table>
</td>
</tr>
</table>
我制作了现在我添加按钮。我怎么能通过在按钮单击上一一显示显示是