我们需要审视健康不良的潜在原因。

We need to look at the ___underlying reasons for ill health.

潜在原因当然是死亡和腐朽的潜伏威胁，这促使科学家研究新方法来推迟死亡年龄。

The ___underlying reason is of course a lurking threat of death and decay, which keeps scientists investigating new methods to postpone the age of death.

冲突的根本原因是缺乏沟通。

The ___underlying cause of the conflict was a lack of communication.