Although there is some evidence that artery damage caused by second-hand smoke in adults may be reversible, LaVan says it's unclear whether that's also true for adolescents.

VOA: standard.2010.03.04

And so, he attempts to defend this position, justify it to his disciples who are worried that it may not be true.

所以,他试图捍卫他的观点,并试图说服,那些怀疑这一点的学生们

耶鲁公开课 - 死亡课程节选