请教大侠 获取JSON返回数据问题

<script type="text/javascript">
<!--
var xmlhttp;
// 创建XMLHTTPRequest对象
function createXMLHTTPRequest()
{
if(window.ActiveXObject)//②如果当前浏览器为IE
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHTTPRequest)//③如果是其他浏览器
{
xmlhttp = new XMLHTTPRequest();
}
}

function getInfo()
{
var bh =document.getElementById("bh").value;
var name=document.getElementById("name").value;

createXMLHTTPRequest();
if ((bh == null) || (bh == "")) return;
var url = "1.asp?bh=" + escape(bh);
url=url + "&name=" + name;
xmlhttp.open("GET", url, true);
xmlhttp.onreadystatechange = returnInfo;
xmlhttp.send(null);
}

function returnInfo()
{
if(xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
var info = xmlhttp.responseText;
// shownr.innerHTML = info;
//返回 info = {"traderates_get_response":{"trade_rates":{"trade_rate":[{"content":"很好！","nick":"平地","result":"good","valid_score":false},{"content":"不错！","nick":"平地","result":"good","valid_score":true}]},"total_results":2}}

showscore.innerHTML = valid_score;
shownick.innerHTML = nick;
showcontent.innerHTML = content;
showresult.innerHTML = result;
}
}
-->
</script>
<input name="bh" type="hidden" id="bh" >
<input name="name" type="hidden" id="name" >
<body onLoad="getInfo()">

页面输出，如：
<table width="100%" border="0" cellspacing="0" cellpadding="5">
<tr>
<td>nick</td>
<td>score</td>
<td>result</td>
<td>result</td>
</tr>
<tr>
<td><span id="shownick"></span>
</td>
<td><span id="showscore"></span>
</td>
<td><span id="showresult"></span>
</td>
<td><span id="showcontent"></span>
</td>
</tr>
</table>

</body>
</html>