lì / shǐ / kè / shàng / lǎo / shī / jiǎng / jiě / le / sù / fǎn / yùn / dòng / de / bèi / jǐng / hé / yǐng / xiǎng

历史课上，老师讲解了肃反运动的背景和影响。

In history class, the teacher explained the background and impact of the purge of counterrevolutionaries.