Staff members transfer packed vegetables at a cooperative in Gu'an County, north China's Hebei Province, June 19, 2020. Located near Beijing, these three counties including Yongqing, Gu'an and Xianghe of Langfang are key bases of vegetable supply to the capital. Recently, Langfang has enhanced quality control to ensure Beijing's market supply and vegetable safety. (Xinhua/Zhang Wei)

Staff members pack vegetables at a cooperative in Gu'an County, north China's Hebei Province, June 19, 2020. Located near Beijing, these three counties including Yongqing, Gu'an and Xianghe of Langfang are key bases of vegetable supply to the capital. Recently, Langfang has enhanced quality control to ensure Beijing's market supply and vegetable safety. (Xinhua/Zhang Wei)

Staff members pack vegetables at a cooperative in Gu'an County, north China's Hebei Province, June 19, 2020. Located near Beijing, these three counties including Yongqing, Gu'an and Xianghe of Langfang are key bases of vegetable supply to the capital. Recently, Langfang has enhanced quality control to ensure Beijing's market supply and vegetable safety. (Xinhua/Zhang Wei)

Staff members pick tomatoes at a cooperative in Gu'an County, north China's Hebei Province, June 19, 2020. Located near Beijing, these three counties including Yongqing, Gu'an and Xianghe of Langfang are key bases of vegetable supply to the capital. Recently, Langfang has enhanced quality control to ensure Beijing's market supply and vegetable safety. (Xinhua/Zhang Wei)