看到美联航官网有如下描述，求dp
https://www.united.com/ual/en/us/fly/travel/notices.html
Non-Functioning WeChat Health App*
- If the WeChat health app is functional, Chinese nationals that present the green QR code with blue HS writing are authorized to board.
- Only if the app no longer functions, but the traveler presents a printed version or digital version (i.e. photo snapshot) of their boarding QR code (green code with blue HS writing), that is sufficient to allow boarding
- Only if the app no longer functions, if the traveler can present a test result paper and verbally confirms they have complied with China’s test requirements that is sufficient to allow boarding