How do you get reliable updates when both mobile data and internet fail? / 手机网络和互联网都中断时，你怎样获得可靠信息？

Which combinations of battery radio, local authorities, neighbors, posted notices, or pre-agreed contacts worked in practice? Avoid sharing emergency-frequency misuse advice. 电池收音机、当地官方、邻里、张贴通知或预先约定的联系人，哪些组合真正有效？请勿分享滥用应急频率的做法。