Snowmaking machines work at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)

Snowmaking machines work at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)

Snowmaking machines work at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)

Snowmaking machines work at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)

Snowmaking machines work at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)

A staff member operates snowmaking machines at a ski field in Chongli District of Zhangjiakou City, north China's Hebei Province, Oct. 17, 2020. Ski fields in Chongli are getting ready for the skiing season as the temperature drops these days. (Photo by Wu Diansen/Xinhua)