Silent as a cicada

Harvey Chase went to the back row and looked at Zhao Haodong.
Zhao Haodong was trembling with fear. He stared at the book in front of him, not daring to move or even breathe.
Harvey Chase didn't say anything and turned back to his seat.
This is called self-study, this is what a classroom is.
Not long after, old professor Zhang Zhiyuan came back angrily.
He thought the classroom would be noisy.
But unexpectedly, the classroom was extremely quiet at this moment, and all the...