A teenager from eastern China told his parents he was going on holiday, but secretly travelled with a friend to a flood-stricken region to join relief efforts. Earlier this month, 18-year-old Shanghai student Wu Yulun had just completed the gaokao, China’s national college entrance examination, and was planning a graduation trip. But after seeing an online appeal from a volunteer group in the southwestern Guangxi region, he abandoned those plans and headed for the disaster zone instead. Days of...