<select size=1 name="sd_carboncopy" id="sd_carboncopy">  
          <option value="">无</option>
           <%do while not rs.eof%>     
          <option value="<%=rs("name")%>"><%=rs("name")%></option>
          <%
          rs.movenext
          loop
          rs.close
          %>
          </select> 
        <input  type="button" value="add" onClick="setname('td_carboncopy');">
function setname(obj)
{
    var copy=document.getElementById("sd_carboncopy").value;
    var answer = document.getElementsByName("cp");
        if (copy != ""){
                  var i = answer.length
                  if (i > 0 )
                   {
                   alert(answer[i].value);
                   }
               // for (var i = answer.length-1; i >= 0; i--) {
                     //if (copy != answer[i].value )
                        {
                         document.getElementById(obj).innerHTML += "<input type='checkbox' name='cp' />" + copy ;
                         }
                     // else
                        // {
                        // alert("对不起,你选择了重复的对象!");
                        // }
                //}
        }        
 }