Firefighter Zhang Yu is on duty at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter. (Photos: Xinhua)

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Aerial photo shows a fire engine patrolling on a road in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

A fire engine patrols on a road in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters read books in the activity room of the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Aerial photo shows a fire engine patrolling on a road in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighter Wu Junming plays the guitar in the activity room of the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Aerial photo shows firefighters exercising in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise at the fire station in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Aerial photo shows a fire engine patrolling on a road in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.

Firefighters exercise in Beiji Village of Mohe City, northeast China's Heilongjiang Province, Jan. 13, 2021. Firefighters stick to their post and keep training despite the freezing weather in Mohe, the northernmost city in China, where the temperature is often below minus 40 degrees Celsius in winter.