A brig with scarlet sails travels on the Finnish Gulf coast during a rehearsal for the the Scarlet Sails festivities marking school graduation in St. Petersburg, Russia, early Saturday, June 27, 2020. This year the festival will not be held in the city center, but on the Finnish Gulf. Due to the coronavirus pandemic, there will be no spectators but the event will be broadcast on television. (Photo by Dmitri Lovetsky/AP Photo)

San Diego Ballet School students wear protective masks backstage during a performance of “The Nutcracker”, presented by the San Diego Ballet in a drive-in performance at a parking lot in San Diego, California, December 5, 2020. (Photo by Bing Guan/Reuters)

A dog from the K9 Division of the Sri Lanka Army’s Commando Regiment performs during an event to mark International Children’s Day at a school in Welisara, Colombo, Sri Lanka, 01 October 2016. Sri Lanka marks the Children's Day on 01 October with more emphasis on prevention of child abuse. (Photo by M.A. Pushpa Kumara/EPA)

A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

Frida, a rescue dog belonging to the Mexican Navy, with her handler Israel Arauz Salinas, takes a break while participating in the effort to look for people trapped at the Rebsamen school in Mexico City, on September 22, 2017, three days after the devastating earthquake that hit central Mexico. (Photo by Omar Torres/AFP Photo)

A member of Brazilian samba school “Aguia de Ouro” takes part in a parade at Anhembi sambadrome as part of carnival in Sao Paulo, Brazil, early 25 February 2017. The Sao Paulo Carnival runs from 24 to 28 february 2017. (Photo by Fernando Bizerra Jr./EPA)

Dan Copeland, left, and Alex Morneau of Biddeford, Maine, former high school cheerleaders, perform back flips while enjoying the record breaking heat, Thursday, May 18, 2017, at Old Orchard Beach, Maine. The temperature climbed well into the 90s in many locations throughout the state. (Photo by Robert F. Bukaty/AP Photo)

Freshmen in Zhengzhou Institute of Aeronautical Industry Management head bottles of mineral water for upright stand during military training on September 17, 2015 in Zhengzhou, Henan Province of China. More than 6,800 freshmen in the school are required to take part in the military training. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)