//读取参数:
public string currpage
{
get
  {
    if (Request.Params["currpage"]==null)
        return "index";
    else
      return Convert.ToString(Request.Params["currpage"]).ToLower();
  }
}
//根据参数来动态调用户控件:
switch(currpage)
{
case "index":
    cright = LoadControl("control/right.ascx");
    break;
case "aboutus":        
    cright = LoadControl("control/aboutus.ascx");
    break;
case "certificate":
.....
}