He's dead against the idea.

他坚决反对这个想法。

They were dead against the plan.

他们完全反对这一计划。

His parents are dead against the trip. dead: adv.

完全地，直接地他的父母完全反对这次旅行。

The man is dead against me for some reason or the other.

那人以各种理由死命反对我。

"My family were dead against it," he remembers, laughing.

“我的家人坚决反对，”他笑着回忆道。