Students take oxygen as they review for the upcoming national college entrance examinations at a hospital in Suining, southwest China's Sichuan province, June 5, 2007.

The entrance exam -- commonly known as "gaokao" in Chinese -- is credited as the backbone of China's remarkable reform-era growth in the 30 years since it was restored, despite mounting criticism that it encourages rote learning and puts too much pressure on overburdened adolescents.

Chinese characters on the book read "Chemistry".

Picture taken on June 5, 2007.

(Source: Reuters)