A farmer sits with his twin grandsons in the middle of a field where he is planting crops on the outskirts of the city of Zhuhanzhen in Shandong province April 21, 2011. [Photo/Agencies] 

A woman and her daughter touch a structural model of the earth's core at Nanjing Geological Museum in Nanjing, Jiangsu province April 22, 2011. Earth Day, which is celebrated on April 22 every year, marks an annual effort to raise public awareness about the environment and inspire actions to clean it up. The Chinese characters on the model read "outer core". [Photo/Agencies] 

Policemen stand guard during a campaign to destroy pornographic and pirated publications in Beijing April 22, 2011. [Photo/Agencies]