Students exercise in body training at Bishan Vocational Education Center in Chongqing, southwest China, January 13, 2016. These students were trained to be stewardesses of the high-speed train. (Photo by Xie Jie/Xinhua)

University students demonstrate against the crisis in the public education, budget cuts and a tax reform project announced by the government of Ivan Duque in Medellin, Colombia on December 13, 2018. (Photo by Joaquín Sarmiento/AFP Photo)

Microphones are seen in front of Frida, a female Chihuahua, after the San Francisco Board of Supervisors issued a special commendation naming Frida “Mayor of San Francisco for a Day” in San Francisco, California November 18, 2014. Frida, a previously unknown female Chihuahua, has won her first political office, being named Mayor of San Francisco for the day as part of a campaign to support the city's animal shelter. (Photo by Stephen Lam/Reuters)

Five year old Michael Esteban and his mother Kari Esteban, crawl through a 40-foot long, 4-foot high replica of a human colon on July 11, 2003 in Seattle. The colon is used to educate people on colorectal cancer. (Photo by Ron Wurzer/Getty Images)

Models promote a condom brand at the first Shenzhen s*x Culture Festival on September 21, 2007 in Shenzhen of Guangdong Province, China. The festival aims to increase awareness about reproductive health and popularise s*x education. (Photo by China Photos/Getty Images)

Two children jumping through a water hydrant's shower on a New York street. They have come from a neighbouring co-educational playgroup organised by the city's Police Department. (Photo by Orlando/Getty Images). 1950

U.S. President Donald Trump boards Air Force One to depart for Vietnam from Beijing Airport in Beijing, China on November 10, 2017. (Photo by Jonathan Ernst/Reuters)