后台怎么控制前台select的选中项

后台如何控制前台select的选中项
假如我前台有一个
<select   id= "ddl ">
          <option   value= "111 "> aaa </option>
          <option   value= "222 "> bbb </option>
          <option   value= "333 "> ccc </option>
</select>

我在后台如何改变它的选中项？

就假如我要在Page_Load()方法里设置它的选中项为第2项
protected   void   Page_Load(object   sender,   EventArgs   e)
{
         
}

------解决方案--------------------------------------------------------
<select id= "ddl " runat= "server ">
<option value= "111 "> aaa </option>
<option value= "222 "> bbb </option>
<option value= "333 "> ccc </option>
</select>

----------------------------

protected void Page_Load(object sender, EventArgs e)
{
ddl.Value = "222 "; //使得bbb选中
}