manifestation|manifestations

发烧是流感的常见表现之一。

Fever is a common ___manifestation of the flu.

频繁头痛可能是压力的表现之一。

Frequent headaches can be one of the ___manifestations of stress.

她的微笑是内心幸福最真实的体现。

Her smile is the purest ___manifestation of inner happiness.