Qián / wǎng / yì / qū / lǚ / xíng / qián / tā / xiān / liǎo / jiě / le / huáng / rè / bìng / de / yù / fáng / fāng / fǎ

前往疫区旅行前，他先了解了黄热病的预防方法。

Before traveling to an affected area, he learned how to prevent yellow fever.