Instead of saying " university" 15 times in your essay, you might want to say: " academic centres" , or " an academic program" , or " institutes of higher learning" , or an " educational institution" , or " school" , " college" , " academy" .
在你的论文中,为了替换掉重复使用15次的“大学”,你可能想说成:“学术中心”,或者“学业计划”,或“高等教育机构”,或者“教育机构”,还或者“学校”,“大学”,“学院”。