In this aerial photo taken on June 26, 2018 shows students attend an outdoor drawing activity in a sunflower field in Nandu Village of Nangong, north China's Hebei Province. In recent years, authorities in Nangong have made efforts to build an economy that integrates tourism with agricultural industries. (Xinhua/Zhu Xudong)

Students attend an outdoor drawing activity in a sunflower field in Nandu Village of Nangong, north China's Hebei Province, June 26, 2018. In recent years, authorities in Nangong have made efforts to build an economy that integrates tourism with agricultural industries. (Xinhua/Zhu Xudong)

A tourist poses for selfies in a sunflower field in Nandu Village of Nangong, north China's Hebei Province, June 26, 2018. In recent years, authorities in Nangong have made efforts to build an economy that integrates tourism with agricultural industries. (Xinhua/Zhu Xudong)

A student attends an outdoor drawing activity in a sunflower field in Nandu Village of Nangong, north China's Hebei Province, June 26, 2018. In recent years, authorities in Nangong have made efforts to build an economy that integrates tourism with agricultural industries. (Xinhua/Zhu Xudong)