In this May 14, 2016 photo, children wearing their school backpacks climb on a cliff using a bamboo ladder on their way home from school in Zhaojue county, southwest China's Sichuan province. A village in China's mountainous west where schoolchildren must climb an 800-meter (2,625-foot)-high bamboo ladder secured to a sheer cliff face may get a set of steel stairs to improve it's safety. (Photo by Chinatopix via AP Photo)

Tao Xiangli gets out of his homemade submarine after operating it in a lake on the outskirts of Beijing September 3, 2009. Amateur inventor Tao, 34, made a fully functional submarine, which has a periscope, depth control tanks, electric motors, manometer, and two propellers, from old oil barrels and tools which he bought at a second-hand market. He took 2 years to invent and test the submarine which costs 30,000 yuan ($4,385). (Photo by Christina Hu/Reuters)

Labourers who work nearby nap on a road as cars drive past in Chongqing Municipality, July 23, 2013. (Photo by Reuters/Stringer)

Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

A performer practices her mermaid swim next to a shark in an aquarium after graduating from a mermaid workshop in Guangzhou, Guangdong Province, China December 16, 2016. (Photo by Tyrone Siu/Reuters)

Yu Jietao, 26-year-old wood carver, sits in his homemade wooden car along a street in Guangfeng county of Shangrao, Jiangxi province, China February 9, 2015. The car can travel as fast as 30 km (18.6 miles) per hour, local media reported. (Photo by Reuters/Stringer)

A model walks down the runway at the 13th China International Young Fashion Designers Contest during China Fashion Week on March 25, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

In this photo illustration, an endangered Chinese box turtle which hatched at Bristol Zoo is placed on a box of matches on August 12, 2008 in Bristol, England. It weighs just 15 grams and measures around 4cm long whereas an adult box turtle weighs around 800 grams, measures around 16 cm long and can live up to 50 years. Chinese box turtles are hunted for their meat for use in medicine or as pets and have been listed as endangered on the International Union for Endangered Species Red List. (Photo by Matt Cardy/Getty Images)