"I need to detect the material of the paper of an ancient book before I repair it. In the past, I checked the material of the paper with both my hands and eyes. Now, I can detect the material of the paper by equipment. Then, I select the paper to use to repair the book. The paper should be made with the same materials as the paper in the ancient book. I also dye the selected paper yellow, which is close to the yellow paper of the ancient book," Zhao says.

Hangzhou Public Library has many professional ancient-book repairing machines. However, Zhao still prefers to repair books by hand. Zhao can repair seven or eight pages in a day. Generally, it takes her nearly a month to repair a whole book.

"I have worked as an ancient-book restorer for 20 years. For me, the happiest thing is completing the restoration of a whole book. I will have a sense of accomplishment. Repairing ancient books is 'rescuing history.' The ancient books cannot be passed on to future generations if we do not repair them. In fact, ancient-book repairing is a job that benefits our offspring," says Zhao.