不好意思又继续发问了，
朋友找到了以下的资讯，觉得互相抵触，
他满焦虑的，所以再麻烦大家帮忙解答一下，谢谢！
他DS-2019会在5/1结束，下个program 7/15开始
https://tinyurl.com/tv4l5s8
他对这段有疑惑
What if I have a gap in status?
If your current nonimmigrant status will expire more than 30 days before your F-1 or M-1 program start date and you wish to remain in the United States until your start date, you must find a way to obtain status all the way up to the date that is 30 days before your program start date (“bridge the gap”).
(1)但我觉得这整个网页不适用J-1 student，他们是在讨论“非用于就学”的status？
(2)如果适用于他，就又回到可能要申请B2来填补gap的问题了？
https://tinyurl.com/whtc8ws
他对这段有疑惑
If you are an international exchange visitor (J-1), you may not change your nonimmigrant status if:
You are an exchange visitor and are required to meet the foreign residence requirement, unless you receive a waiver.
(2)他认为他有两年条款221(e)，而且没申请waive，所以不能COS？
https://tinyurl.com/uhp6ht2
他对第二段有疑惑
you may apply to change your nonimmigrant status if you were lawfully admitted to the United States in an eligible nonimmigrant status, your nonimmigrant status remains valid
(3)他想知道remains valid是指到核可前都要valid吗？我觉得是file I-539时valid就好？
https://imgur.com/a/Xx4DXoZ
这间学校DSO直接说如果你的status在I-20 start date的30天前就结束，
COS will most likely be denied
(4)这是真的吗？
(5)我个人是认为有试有机会，被deny就离开美国申请visa，但没试就没机会啦...
他怕很接近7/15时被deny，如果大使馆早就回复签证面试预约，
到7/15才离开美国申请visa反而会无法准时开始program，
如果COS不安全，倒不如不要。
跟我的想法完全相反，我是觉得离开美国以目前疫情状况，未知数更多XD
发问多次，麻烦各位了，谢谢！