A staff member displays a postmarked first day cover with a "Guangdong-Hong Kong-Macao Greater Bay Area" special stamp at Hong Kong General Post Office in south China's Hong Kong, Sept. 26, 2019. The "Guangdong-Hong Kong-Macao Greater Bay Area" special stamp sheetlets were issued on Thursday in post offices of Hong Kong, Guangzhou and Macao. (Xinhua/Luo Huanhuan)