Visitors are seen waiting outside the Panda House in Copenhagen Zoo, Denmark, April 11, 2019. Danish Queen Margrethe II officially opened the Panda House at Copenhagen Zoo on Wednesday. Male Xing Er, a 5-year-old, and female Mao Er, a 4-year-old, left the southwestern Chinese city of Chengdu on April 4 and headed to their new home at Copenhagen Zoo. (Xinhua/Guo Chen)