Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday. (Photos: Xinhua)

Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday.

Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday.

Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday.

Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday. )

Tourists ride camels in the Crescent Spring and Mingsha Sand Dune scenic area in Dunhuang, northwest China's Gansu Province, on May 1, 2019, the first day of the four-day May Day holiday.

Tourists view Rhododendron flowers in Huama Village of Gandong Township, Rongshui Miao Autonomous County, south China's Guangxi Zhuang Autonomous Region, May 1, 2019, the first day of four-day May Day holiday.

Tourists watch a music band performance on the bank of the Huangpu River in east China's Shanghai, May 1, 2019, the first day of four-day May Day holiday.

Villagers demonstrate a ploughing ceremony for tourists in Huama Village of Gandong Township, Rongshui Miao Autonomous County, south China's Guangxi Zhuang Autonomous Region, May 1, 2019, the first day of four-day May Day holiday.

Tourists watch a music band performance on the bank of the Huangpu River in east China's Shanghai, May 1, 2019, the first day of four-day May Day holiday.

Tourists visit a beach in Haikou, south China's Hainan Province, May 1, 2019, the first day of four-day May Day holiday.

A young tourist has fun at a beach in Haikou, south China's Hainan Province, May 1, 2019, the first day of four-day May Day holiday.

Tourists visit the Xiangyuan Garden scenic area in Suixian County, central China's Henan Province, May 1, 2019, the first day of four-day May Day holiday.

Villagers perform a folk dance for tourists in Huama Village of Gandong Township, Rongshui Miao Autonomous County, south China's Guangxi Zhuang Autonomous Region, May 1, 2019, the first day of four-day May Day holiday.

Tourists visit a cultural and creative park in southwest China's Chongqing, May 1, 2019, the first day of four-day May Day holiday.

Tourists take photos of street sculptures in southwest China's Chongqing, May 1, 2019, the first day of four-day May Day holiday.

A tourist takes photos of light-rail train in southwest China's Chongqing, May 1, 2019, the first day of four-day May Day holiday.