如何利用类似cols-xs-4的方式减少宽度并且独占一行？
这里的代码好像都是很宽，那么我就想用cols-xs-x的方式来修改它们的宽度，结果发现它们并排显示了，如何让他们独占一行显示？加BR不行
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>表单控件状态——焦点状态</title>
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<link rel="stylesheet" href="style.css">
</head>
<body>
<h1>示例1</h1>
<form role="form">
<div class="form-group has-success has-feedback" style="width:25%;">
<label for="success">成功状态</label>
<input type="text" id="success" placeholder="成功状态">
<span class="glyphicon glyphicon-ok form-control-feedback"></span>
</div>
<div class="form-group col-xs-4 has-warning has-feedback">
<label for="warning">警告状态</label>
<input type="text" id="warning" placeholder="警告状态">
<span class="glyphicon glyphicon-warning-sign form-control-feedback"></span>
</div>
<div class="form-group has-error has-feedback">
<label for="error">错误状态</label>
<input type="text" id="error" placeholder="错误状态">
<span class="glyphicon glyphicon-remove form-control-feedback"></span>
</div>
</form>
</body>
</html>
