lì / shǐ / kè / shàng / lǎo / shī / jiè / shào / le / Xīn / chǒu / Tiáo / yuē / de / qiān / dìng / bèi / jǐng

历史课上，老师介绍了《辛丑条约》的签订背景。

In history class, the teacher introduced the background to the signing of the Boxer Protocol.