错在那里
<html><head>
<script language="javascrip">
function block(id,id2,value)
{
if(value=="隐藏")
{
eval("id.style.display=\"none\"");
eval("id2.value=\""显示\"");
}
else
{
eval("id.style.display=\""block\"");
eval("id2.value=\""隐藏\"");
}
}
</script>
</head>
<body>
<input type="button" id="btn1" value="隐藏" onclick="block(txt1,btn1,this.value)">
<input type="text" id="txt1">
</body>
</html>