Senior high school students study to prepare for the college entrance exams in a classroom in No. 2 Middle School of Hengshui, north China's Hebei Province, May 15, 2016. The exam is to take place early next month. (Xinhua/Zhu Xudong)

Senior high school students study to prepare for the college entrance exams in a classroom in No. 2 Middle School of Hengshui, north China's Hebei Province, May 15, 2016. The exam is to take place early next month. (Xinhua/Zhu Xudong)

Senior high school students study to prepare for the college entrance exams in a classroom in No. 2 Middle School of Hengshui, north China's Hebei Province, May 15, 2016. The exam is to take place early next month. (Xinhua/Zhu Xudong)

Senior high school students study to prepare for the college entrance exams in a classroom in No. 2 Middle School of Hengshui, north China's Hebei Province, May 15, 2016. The exam is to take place early next month. (Xinhua/Zhu Xudong)