Workers are seen on the assembly line of a drilling equipment manufacturer in the Xuanhua district of Zhangjiakou, North China's Hebei Province on Monday. The district has been supporting an upgrading of the local drilling machinery industry, helping companies to develop new products and explore overseas markets. The district is home to 90 major drilling rig businesses, whose products are shipped to over 30 countries and regions including Europe and the US. Photo: cnsphoto