Lì / shǐ / kè / shàng / lǎo / shī / xiáng / xì / jiè / shào / le / bā / èr / sān / pào / zhàn / de / bèi / jǐng

历史课上，老师详细介绍了八二三炮战的背景。

In history class, the teacher explained the background of the 823 Artillery Bombardment in detail.