用javascript如何给span赋值呢？一般有两种方法：
1>输出html
<body οnlοad="s()">
<span id="hello"></span><script language="javascript">
function s(){ document.getElementById("hello").innerHTML = "<iframe src= height=400 width=300></iframe>";}
</script>2>输出文本
<body οnlοad="s()">
<span id="hello"></span><script language="javascript">
function s(){ document.getElementById("hello").innerText = "hello world";}
</script>