How does zhu wenli change over the course of the story? ?

She turns into to a violent, coarse person.

In the story "A Decade," we are told the story of a writer who visits his old town in China during the 1960s. This was the period of the Cultural Revolution. The narrator reflects on her teacher, Zhu Wenli, a young woman who got sent to a labor camp because of her. The narrator decides to look for her teacher. She wants to apologize and show that she has not been forgotten. However, the experiences of the labor camp have changed Zhu Wenli. She is now a hardened, violent woman, very different from the person she was before.

cockroaches and rats often are a symbol for things that are disgusting or vile. though i don't know which play you are talking about, i hope this !