A new monorail service in Houston, Texas, ready for its inaugural service. (Photo by Evans/Three Lions/Getty Images). Circa 1950

Residents make their way along a fence as they try to cross a flooded street after heavy rainfall hit Wuhan, Hubei province, China, July 23, 2015. Severe downpours hit the city on Thursday, flooding streets and shutting down public transportations, local media reported. (Photo by Reuters/China Daily)

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

Recruits who earned a place in the Motivation Platoon struggle through water and muck on their way to becoming a Marine or going into some other line of work, October 7, 1971. (Photo by Eddie Adams/AP Photo)

Woman waking up with two men in her bed. (Photo by Ilbusca/Getty Images/iStockphoto)

Sеxy brunet striptease dancer dancing lap dance in front of man. (Photo by Blue SkyImages/Getty Images)

High angle view of a young woman reading in a bathtub, turning page, enjoying time with herself. Candles and red wine. Valentines day concept, International womans day. (Photo by Vuk Saric/Getty Images)