yán / jiū / rén / yuán / tōng / guò / niú / dòu / bìng / de / xiāng / guān / yán / jiū / wèi / yù / fáng / tiān / huā / tí / gōng / le / xiàn / suǒ研究人员通过牛痘病的相关研究,为预防天花提供了线索。Researchers gained clues for preventing smallpox through studies related to cowpox.