图象怎么没有改变
<html><head>
<title>Image Object</title>
<script language="javascript">
//pre-cache for images
image1=new Image(120,89)
image1.src="file:///F|/myweb/images/1.jpg"
image2=new Image(120,89)
image2.src="file:///F|/myweb/images/2.jpg"
image3=new Image(120,89)
image3.src="file:///F|/myweb/images/3.jpg"
image4=new Image(120,89)
image4.src="file:///F|/myweb/images/4.jpg"
//load an image chosen from select list
function loadCached(list)
{
var img=list.options[list.selectIndex].value
document.thumbnail.src=eval(img+".src")
}
</script>
</head>
<body>
<H2>Image Object</H2>
<IMG SRC="file:///F|/myweb/images/1.jpg" name="thumbnail" height="89" width="120">
<form>
<select name="cached" onChange="loadCached(this)">
<option value="image1">Bands
<option value="image2">Clips
<option value="image3">Lamp
<option value="image4">Erasers
</select>
</form>
</body>
</html>
这是小弟写的一个关于图象变化选择的代码，怎么写了好象没有改变啊！好奇怪啊！！
高手帮我看看哪里出错拉！！谢谢啊
