bootstrap的下拉多选框如何使用

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.10.0/css/bootstrap-select. 
min.css">
<!-- Latest compiled and minified JavaScript -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.10.0/js/bootstrap-select.min.js"></script>
<!-- (Optional) Latest compiled and minified JavaScript translation files -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.10.0/js/i18n/defaults-zh_CN.min.js"></script>

<select class="selectpicker" title="请选择">
 <option value="1">广东省</option>
 <option value="2">广西省</option>
 <option value="3">福建省</option>
 <option value="4">湖南省</option>
 <option value="5">山东省</option> 
</select>

<select class="form-control selectpicker" data-live-search="true" multiple>
 <optgroup label="广东省">
 <option value="1">广州市</option>
 <option value="2">深圳市</option>
 <option value="3">珠海市</option>
 </optgroup> 
 <optgroup label="广西">
 <option value="1">南宁市</option>
 <option value="2">柳州</option>
 <option value="3">桂林市</option>
 </optgroup> 
 <optgroup label="山东">
 <option value="1">烟台</option>
 <option value="2">青岛</option>
 <option value="3">济南</option>
 </optgroup> 
</select>

<select class="selectpicker" data-style="btn-primary">
 ...
</select>
<select class="selectpicker" data-style="btn-info">
 ...
</select>
<select class="selectpicker" data-style="btn-success">
 ...
</select>
<select class="selectpicker" data-style="btn-warning">
 ...
</select>
<select class="selectpicker" data-style="btn-danger">
 ...
</select>