Skiers practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Hu Huhu)

Skiers of Poland practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Hu Huhu)

Skiers practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Deng Hua)

Skiers of France practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Mu Yu)

Skiers of Canada practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Hu Huhu)

Skiers practise during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Mou Yu)

A skier practises during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Deng Hua)

A Chinese skier practises during a training session at National Cross-Country Skiing Centre in Zhangjiakou, north China's Hebei Province, Jan. 29, 2022. (Xinhua/Deng Hua)