25.【2019 •天水市】Most of the villagers took part in the Dragon Boat races       9:00 a. m.        the morning of June 7.
   A. at; in B. on; on C. on; in D. at; on
【答案】D
【解析】句意：大多数村民都参加了6月7日上午9点的龙舟比赛。在具体几点钟前用介词 at；the morning of June 7是指6月7日的上午，在具体某一天的早上用介词 on。故答案为D。