Those planning a trip to remote areas, or intending to live in countries where drinking water is not readily available, should know about the various possible methods for making water safe.
那些計(jì)劃去偏遠(yuǎn)地區(qū)旅行,或在飲用水不現(xiàn)成的國(guó)家居住的人,應(yīng)該知道如何使水適于飲用的各種辦法。