His efforts were noticed by Cao Yan, one of the school's English professors, who was moved by his determination but not so impressed with his pronunciation.

The professor gave him permits to take free English training classes and encouraged him to sit for the college entrance exam for adults' continuing studies. She also talked with the administrator of the security team to make adjustments to his shift so he could have time to take the course.

"I do not want you to feel grateful to me, I need you to take concrete action and study hard," Cao told Zhang.

He started to take the English courses and later decided to take the college entrance exam. He tried to enroll in the university's law school.

"Between work and preparing for the exam, I often ran between classes, and I was too busy with work to eat," Zhang said. "But I didn't feel it was tough. On the contrary, it was quite fulfilling."

However, he did not pass the exam, so he began to prepare for the self-taught exam to obtain a higher vocational degree. He needed to pass 13 courses to get the degree.

"Although I could not get a bachelor's degree, I believed as long as I worked harder, I could get a vocational degree," Zhang said.

He often stayed up late to study. When the dormitory's lights went out, he continued to read by flashlight. "I only slept for three to four hours a day. It was tough, but it was nothing that I could not handle," he said.

In 1998, he passed all the required tests and earned his vocational degree from PKU. A year later, he decided to return to his hometown in Changzhi, where he worked at several vocational schools.

In 2015, Zhang decided to establish a vocational secondary school with four of his friends. His goal is to provide opportunities to more students who failed to enter high school.