What are the sentences that describe being serious in class?

1. From time to time, the teacher's lecture and classmates' reading sound came from the classroom, like a harmonious ensemble.

There was silence in the classroom, only the pen tip rustled on the paper, just like whispering.

He buried himself in his homework again, and the room was quiet, except for the rustling of pens on the paper.

Students sit in the classroom and listen attentively to the teacher's lecture, just like dozens of flowers are quietly watered by hard gardeners.

5. Xiao Fei sat in his seat, writing and writing. There seems to be a steady stream of spring water flowing out of the pen. In less than one class, I actually wrote a composition.