Visitors view stamp exhibits during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)

A visitor views stamp exhibits during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)

A man views stamp exhibits during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)

Visitors talk with a representative of a French exhibitor during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)

Visitors view stamp exhibits during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)

Visitors view stamp exhibits during the 2019 World Stamp Exhibition held in Wuhan, capital of central China's Hubei Province, June 11, 2019. The 2019 World Stamp Exhibition kicked off here on Tuesday. Nearly 4,700 exhibits from more than 80 countries and regions are showcased during the event. (Xinhua/Cheng Min)