Lì / shǐ / kè / shàng / lǎo / shī / jiè / shào / le / yì / tāi / zhì / shí / shī / de / bèi / jǐng / hé / yǐng / xiǎng

历史课上，老师介绍了一胎制实施的背景和影响。

In history class, the teacher explained the background and effects of the one-child policy.