Exhibits are seen at the Hannover Industrial Exposition in Hannover, Germany, on April 8, 2013. With the theme of Integrated Industry, Hannover Messe 2013 has attracted the participation of approximately 6,500 exhibitors, making this year's exposition the largest in recent ten years. (Xinhua/Ma Ning)

Visitors look at an electric car with a grass shell during the Hannover Industrial Exposition in Hannover, Germany, on April 8, 2013. With the theme of Integrated Industry, Hannover Messe 2013 has attracted the participation of approximately 6,500 exhibitors, making this year's exposition the largest in recent ten years. (Xinhua/Ma Ning)

Visitors look at equipments on display during the Hannover Industrial Exposition in Hannover, Germany, on April 8, 2013. With the theme of Integrated Industry, Hannover Messe 2013 has attracted the participation of approximately 6,500 exhibitors, making this year's exposition the largest in recent ten years. (Xinhua/Ma Ning)

Visitors look at windmill models during the Hannover Industrial Exposition in Hannover, Germany, on April 8, 2013. With the theme of Integrated Industry, Hannover Messe 2013 has attracted the participation of approximately 6,500 exhibitors, making this year's exposition the largest in recent ten years. (Xinhua/Ma Ning)

A visitor walks past a poster at the Hannover Industrial Exposition in Hannover, Germany, on April 8, 2013. With the theme of Integrated Industry, Hannover Messe 2013 has attracted the participation of approximately 6,500 exhibitors, making this year's exposition the largest in recent ten years. (Xinhua/Ma Ning)