Pupils demonstrate smiley cards to greet the upcoming World Smile Day at a primary school in Qinhuangdao, north China's Hebei Province, May 7, 2019. (Photos: Xinhua)

World Smile Day is celebrated on May 8 every year.

A kid demonstrates a handmade smiley card to greet the upcoming World Smile Day at a kindergarten in Zhenjiang, east China's Jiangsu Province, May 7, 2019.

Kids demonstrate smiley cards to greet the upcoming World Smile Day at a kindergarten in Zigui County, central China's Hubei Province, May 7, 2019.

Pupils demonstrate smiley cards to greet the upcoming World Smile Day at a primary school in Handan, north China's Hebei Province, May 7, 2019.

Pupils demonstrate smiley cards to greet the upcoming World Smile Day at a primary school in Handan, north China's Hebei Province, May 7, 2019.