They say their findings show that even low levels of smoke may cause behavior problems in children with asthma or others at risk.

VOA: special.2009.01.13

Well, you show the thing that would cause you to have the fear without the unconditioned stimulus.

找出在非条件刺激不存在的情况下,能够使你感到恐惧的东西。

耶鲁公开课 - 心理学导论课程节选