lǎo / shī / zài / tiān / wén / kè / shàng / jiè / shào / le / běi / dǒu / qī / xīng / zhōng / de / tiān / jī

老师在天文课上介绍了北斗七星中的天玑。

The teacher introduced Tianji, one of the stars in the Big Dipper, in astronomy class.