The question is, "If you're naturally exposed to antigen wouldn't this happen anyway?"

她的问题是,在自然条件下,如果接触某种抗原,那么就是否就不发生二次免疫

耶鲁公开课 - 生物医学工程探索课程节选

If these are the conditions for contact, to what extent are they met in the university setting between, say blacks and whites, people from the American South versus people from the American North, people from other countries versus people from the United States?

如果大学环境里有这些接触的条件，有多少是属于促成因素的？,例如在黑人和白人之间，来自美国南方的人,和来自美国北方的人之间，外国的学生,和美国的学生之间？

耶鲁公开课 - 心理学导论课程节选