Bootstrap弹出框modal上层的输入框不能获得焦点问题的解决方法

<div class="modal fade" tabindex="0" role="dialog" id="myModal" data-backdrop="static">  <div class="modal-dialog modal-lg">   <div class="modal-content">   <div class="modal-header">    <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>    <h4 class="modal-title" id="myModalLabel">添加学校</h4>   </div>   <div class="modal-body">    <form class="form-horizontal" name="myForm" novalidate>    <input type="hidden" ng-model="entity.SchID" />    <div class="form-group">     <label for="SchName" class="col-sm-2 control-label">学校名称：</label>     <div class="col-sm-10">     <input type="text" required ng-minlength="3" ng-maxlength="30"      class="form-control"      ng-model="entity.SchName" name="SchName" placeholder="长度3-30">     <span class="text-danger" ng-show="myForm.SchName.$dirty && myForm.SchName.$invalid">      <span ng-show="myForm.SchName.$error.required">名称是必须的</span>      <span ng-show="myForm.SchName.$error.minlength">最小长度3</span>      <span ng-show="myForm.SchName.$error.maxlength">最大长度30</span>     </span>     </div>    </div>     <div class="form-group">     <label for="WebSite" class="col-sm-2 control-label">学校官网：</label>     <div class="col-sm-10">     <input required type="url" class="form-control" ng-model="entity.WebSite" name="WebSite"      placeholder="链接地址" />     <span class="text-danger" ng-show="myForm.WebSite.$dirty && myForm.WebSite.$invalid">      <span ng-show="myForm.WebSite.$error.required">姓名是必须的</span>      <span ng-show="myForm.WebSite.$error.url">链接格式不正确</span>     </span>     </div>    </div>     <div class="form-group">     <label for="FoundTime" class="col-sm-2 control-label">建校时间：</label>     <div class="col-sm-10">     <input required type="number" class="form-control" ng-model="entity.FoundTime" name="FoundTime"      placeholder="年份" />     <span class="text-danger" ng-show="myForm.FoundTime.$dirty && myForm.FoundTime.$invalid">      <span ng-show="myForm.Summary.$error.required">姓名是必须的</span>      <span ng-show="myForm.Summary.$error.number">请输入数字（年份）</span>     </span>     </div>    </div>    <div class="form-group">     <label class="col-sm-2 control-label">入学时间：</label>     <div class="col-sm-10">     <div class="selectBox" id="selectMonth"></div>     <input type="hidden" name="Province" ng-model="entity.MonthList" />     </div>    </div>    </form>   </div>   <div class="modal-footer">    <button type="button" class="btn btn-success" ng-disabled="myForm.$invalid" ng-click="addOrUpdate()">保存</button>    <button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>   </div>   </div>  </div>  </div>