<prompt> Translate the following text to EnglishKwa mfano, dawa ya kupunguza maji mwilini kwa kutumia mdomo imechunguzwa na kutumiwa kutibu ugonjwa wa kuhara katika nchi zinazoendelea.  <response>: Cheap oral hydration, for example, has been studied and used to treat dehydration for diarrheal illness in developing countries. 