She's always been kind to me—I can't just turn______on her now that she needs my help. （2007年考试真题）
【正确答案】 A
【答案解析】解析：本题考查动词turn固定搭配，turn one's back on／upon意为“对……置之不理”，符合句意。B项，turn one's head意为“回头”；C项应是turn one's eye to“把目光投向……”；D项为错误搭配。