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>