A mother and daughter walk with an umbrella in hand in Baoding City, North China's Hebei Province, May 11, 2013. A hot wave hit Hebei these days, with the highest temperature in parts of the province reaching 37 degrees Celsius. (Xinhua/Zhu Xudong)

A woman holding an umbrella walks on the street in Baoding City, North China's Hebei Province, May 11, 2013. A hot wave hit Hebei these days, with the highest temperature in parts of the province reaching 37 degrees Celsius. (Xinhua/Zhu Xudong) 

A citizen walks under the hot sun in Baoding City, North China's Hebei Province, May 11, 2013. A hot wave hit Hebei these days, with the highest temperature in parts of the province reaching 37 degrees Celsius. (Xinhua/Zhu Xudong)