dāo / gēng / huǒ / zhòng / suī / rán / yuán / shǐ / dàn / zài / dāng / shí / shì / yǒu / xiào / de / gēng / zuò / fāng / fǎ

刀耕火种虽然原始，但在当时是有效的耕作方法。

Although slash-and-burn is primitive, it was an effective farming method at the time.