如何使用JQuery向Bootstrap Modal body添加段落？

<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h4 class="modal-title" id="myModalLabel">Modal标题</h4>
      </div>
      <div class="modal-body">
        <!-- 这里是Modal body的内容 -->
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">关闭</button>
      </div>
    </div>
  </div>
</div>

$(document).ready(function(){
  $("#myModal").on("show.bs.modal", function(){
    $(".modal-body").append("<p>这是一个段落。</p>");
  });
});

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">
  打开Modal
</button>