Cornelius left with his subordinates, and Dumbledore called Ye Feng back to class. The next day, Ye Feng heard that the Ministry of Magic had taken the Dementors back, because on the very night they arrived, a Dementor had gone out of control and attacked a Hogwarts student.
Fortunately, he was not alone at the time, so although that unlucky fellow was sucked unconscious on the spot, the Dementor was blasted into fine dust by a talisman used by his classmate. That unlucky fellow was still so weakened from the ordeal that he wobbled whenever he walked.
Harry: Thanks, please don't tag me.
Chapter 152