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<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
// 打印出1000-2000年中所有的闰年，并以每行四个数的形式输出
var i = 0
for(var a = 1000 ; a <= 2000 ; a++){
if(a % 4 == 0 && a % 100 != 0 || a % 400 == 0){
document.write(a + ' ' + '')
i++
if(i % 4 == 0){
document.write('<br>')
}
}
}
</script>
</body>
</html>
