Scientists don't know what causes it, but besides a genetic predisposition, they are now focusing on environmental exposure, or a combination of the two.

VOA: standard.2010.08.09

We might wonder what causes it.

我们会想这个的原因是什么。

耶鲁公开课 - 死亡课程节选

And he claimed it causes an unpleasant emotional state, what he described as "dissonance."

他认为这会让人进入一种情绪不安的状态，他称之为“失调”

耶鲁公开课 - 心理学导论课程节选

For example, how cancer diagnosis has improved, what are some of the causes of cancer in the environment around us and how can we protect ourselves from it, and we'll talk about treatments for it as well.

例如癌症的诊断手段是如何进步的,我们周围环境中有哪些致癌因素,以及我们如何保护自己免受其害,我们也会讨论到癌症的治疗手段

耶鲁公开课 - 生物医学工程探索课程节选