niú / dòu / bìng / céng / jīng / shì / yì / zhǒng / yán / zhòng / wēi / xié / ér / tóng / jiàn / kāng / de / chuán / rǎn / bìng

牛痘病曾经是一种严重威胁儿童健康的传染病。

Cowpox was once an infectious disease that seriously threatened children's health.