插入图片

<figure class="wp-block-image size-large"><img src="图片链接;impolicy=Letterbox&amp;imcolor=%23000000&amp;letterbox=false" alt=""/></figure>

插入外部视频并居中

<h1 style="text-align:center">BILIBILI视频嵌入</h1>
<div style="text-align:center" >
<iframe id="video" src="//player.bilibili.com/player.html?aid=289429224&bvid=BV1Nf4y147JD&cid=306065089&page=1" scrolling="no" border="0" frameborder="no" framespacing="0" allowfullscreen="true" width="100%"> </iframe>
<script type="text/javascript">document.getElementById("video").style.height=document.getElementById("video").scrollWidth*0.65+"px"</script>
</div>

.video-container {
    position: relative;
    height: 0;
    padding-top: 20px;
    padding-bottom: 93%;
    overflow: hidden;
}
.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
<h1 style="text-align:center">优酷视频嵌入</h1>
<div class="video-container">
    <iframe src="http://player.youku.com/embed/XNDU0NDQxNzA3Mg==" width="100%" frameborder="0"></iframe>
    </div>

PDF插入

<object data="下载地址#toolbar=0" type="application/pdf" width="100%" height="500px">
<p><b>返回内容</b>: 该浏览器不支持PDFs.请尝试使用电脑端浏览器打开如:chrome，adge
<!--<a href="下载地址">Download PDF</a>.--></p>
</object>