Children watch the detection of a drug-sniffing dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking. (Photos: Xinhua)

A child tries to touch a detection dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking.

A child takes a selfie with a detection dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking.

Children watch the detection of a drug-sniffing dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking.

Children watch the detection of a drug-sniffing dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking.

Children watch the detection of a dog at the Guangzhou Customs in Guangzhou, capital of south China's Guangdong Province, June 24, 2018. The Guangzhou Customs and the Guangzhou No. 2 Children's Palace on Sunday jointly held the open day activity for children to get to know the fight against drug trafficking.

Guangzhou customs held "Drug Dogs Open Day" campaign in cooperation with the Second Children's Palace in Guangzhou on June 24. (Photos: VCG)

Guangzhou customs held "Drug Dogs Open Day" campaign in cooperation with the Second Children's Palace in Guangzhou on June 24.