Workers weld components at a factory of Harbin Electric Machinery Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 2, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province. (Photos: Xinhua)

A worker is seen at a boiler production factory of Harbin Boiler Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 4, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of Harbin Electric Machinery Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 2, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 29, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

Laborers work at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 28, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of Harbin Electric Machinery Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 2, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

People work at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 28, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A laborer works at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 28, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of Harbin Electric Machinery Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 2, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 27, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of Harbin Turbine Company Limited in Harbin, northeast China's Heilongjiang Province, Sept. 3, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

People work at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 28, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A laborer works at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 28, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.

A worker welds components at a factory of China First Heavy Industries in Qiqihar, northeast China's Heilongjiang Province, Aug. 29, 2019. The group of photos uses the light and shadow in photography to outline the labor scene of the industrial workers in China's Heilongjiang Province.