最近在填I539表，一共碰到三个地方提到extension or change of status，分别如下：
2. Is this application based on an extension or change of status already granted to your spouse, child or parent?
3. Is this application based on a separate petition or application to give your spouse, child or parent an extension or change of status?
3g. Have you, or any other person included in this application, been employed in the U.S. since last admitted or granted an extension or change of status?
另外也仔细阅读了皮匠老师的博文：http://blog.wenxuecity.com/blogview.php?date=200709&postID=147#I539，感觉还是没有理解清楚extension or change of status的含义。以上3个问题中的extension or change of status是否都是指在美国国内通过填I539表申请EoS/CoS，还是分别具有不同的含义？个人感觉皮匠老师在对问题1的解释中是这么理解的，而对问题2和3阐述的不多，似乎在美国递交I129也算是身份改变。请大侠解惑，多谢了！