Employees work at an assembly line of the north China base of FAW－Volkswagen in north China＇s Tianjin， Jan． 11， 2023． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Zhao Zishuo）

People enjoy snacks at a fair in Jizhou District of north China＇s Tianjin， Jan． 12， 2023． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Li Ran）

People watch a performance at a large commercial complex transformed from an old thermal power plant in north China＇s Tianjin， Jan． 1， 2023． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Sun Fanyue）

This aerial photo taken on Jan． 8， 2023 shows the Jizhou International Ski Resort in North China＇s Tianjin． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Sun Fanyue）

Passengers go through ticket gates at Tianjin West Railway Station in north China＇s Tianjin， Jan． 7， 2023． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Li Ran）

This aerial photo taken on Jan． 10， 2023 shows a container terminal at the Tianjin Port in north China＇s Tianjin． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Zhao Zishuo）

This aerial photo taken on Jan． 5， 2023 shows the construction site of a photovoltaic （PV） power project in North China＇s Tianjin． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Li Ran）

People attend an promotion event for fruits from Vietnam in North China＇s Tianjin， Jan． 13， 2023． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Zhao Zishuo）

This photo taken on Jan． 10， 2023 shows the view of Tianjin Binhai International Airport in north China＇s Tianjin． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Zhao Zishuo）

This aerial photo taken on Jan． 10， 2023 shows the Haihe River bridge， an important channel of freight transport， in Binhai New Area of North China＇s Tianjin． People＇s social and economic activities gradually return to normal after China＇s optimization of its COVID－19 response measures． （Xinhua／Zhao Zishuo）