这是为什么我应用引导选择框
生成的输出
<div class="row">
<div class="col-sm-3 col-md-3">
<label for="degree"><strong>Stage/Level</strong></label>
<select class="form-control" id="sel1">
<option>Select stage/level</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select
</div>
</div>