Protecting herself.

When Xin Mei was a child, Xin Jin was very concerned about her safety. He was afraid that other boys or girls would bully her. So, he had personally sent her to the best self-safety classes in the city.

That was why Xin Mei was a black belt in karate and her kicking and boxing skills were also very strong. She knew how to protect herself.

So, when handkerchief was placed over her nose, she held her breath to not inhale the chloroform. She was an expert swimmer, so it was not a big deal for her to hold her breath for a slightly longer time. 

She took deep gulps of breath when the handkerchief was removed from her nose. Her heart was beating fast out of fear. Her eyes were wide opened and she was trying to adjust them to the darkness enveloping around them.

She was also feeling slightly dizzy because of the little amount of chloroform which she had accidentally inhaled.