                        课程
                    
                        /前端开发
                        
                            /Html5
                        
                        /Canvas 绘制时钟

帮我看看哪有问题？怎么不见圆出现？

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>时钟</title>
    <style type="text/css">
        div{
         text-align: center;
            margin-top: 250px;
        }
        #c1ock{
            width: 200px;
            height: 200px;
            border: 1px solid #cccccc;}
     </style>

</head>
<body>
<div>
    <canvas id="c1ock" ></canvas></div>
<script type="text/javascript">
    var a1=document.getElementById("clock");
    var ctx=a1.getContext("2d");
    var kuan=ctx.canvas.width;
    var gao=ctx.canvas.height;
    var r= width/2;
    function sex() {
        ctx.translate(r,r);
        ctx.beginPath();
        ctx.lineWidth = 10;
        ctx.arc(0,0,r-5,0,2*Math.PI,false);

        ctx.stroke();
    }
   sex();
</script>
</body>
</html>