递归调用怎么就不动了呢，count文本框不动啊。
放到里边怎么运行不了啊。<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>计时器</title>
</head>
<script type="text/javascript">
var num=0;
function startCount() {
document.getElementById('count').value=num;
num=num+1;
document.write("begin run;.");
setTimeout(startCount,5000); //放到里边怎么就不动了呢！
}
startCount();
</script>
</head>
<body>
<form>
<input type="text" id="count" />
</form>
</body>
</html>
