lǎo / shī / yì / dǎ / líng / jiù / zǒu / jìn / jiào / shì / zhǔn / bèi / shàng / dì / yī / jié / kè

老师一打铃就走进教室，准备上第一节课。

As soon as the bell rang, the teacher entered the classroom to prepare for the first lesson.