一个简单的问题

<html><body>
<table border="1" width="100%">
<tr>
<td><input type="radio" checked name="a" OnDblClick="bb('xx');">xx</td>
</tr>
<tr>
<td><input type="radio" name="a" onDBlClick="bb('yy');">yy</td>
</tr>
<tr>
<td id="td1" width="100%"><input type="radio" name="a" onDBlClick="bb('zz');">zz</td>
</tr>
<script language="javascript">
var div1=document.createElement("div");
div1.style.left="800px";
div1.style.position="absolute";
div1.style.width="20%"
div1.style.backgroundColor="red";
div1.innerText="China";
document.getElementById("td1").appendChild(div1);
</script>
</body>
</html>