“多跳网络”让美国人在自然灾害中保护联系

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infrastructure – n. the basic equipment and structures that are needed for a country, area or organization to operate

offline – n. not connected to a computer, a computer network, or the Internet

sovereignty – n. a country's right to govern itself

low-frequency – adj. radio waves with frequencies much lower than the signals normally used in communications equipment

route – n. a path or line of travel