为什么这段代码不起作用！无论我做什么，它都会一直默认，而且我没有看到在 stackoverflow 中没有人遇到与此类似的问题。请帮忙
var age = 20;
switch(age){
case(age<10):
document.getElementById("box").innerHTML = "you are a kid";
break;
case(age>10 && age<=18 ):
document.getElementById("box").innerHTML = "you are teen";
break;
case(age>18):
document.getElementById("box").innerHTML = "you are adult";
break;
default:
document.getElementById("box").innerHTML = "Some thing is broken!!";
}<html>
<head>
</head>
<body>
<div id="box"></div>
<!--External Javascrip-->
<script type="text/javascript" src="script.js"></script>
</body>
</html>