voluntary

完全自愿

To emphasize that there is absolutely no obligation or compulsion.

强调完全没有任何义务或强迫。

完全自愿的

To emphasize that something is wholly based on free will.

强调某事完全基于自由意志。

纯粹自愿

To highlight that the action is motivated only by choice, with no other factors.

强调该行为仅出于自愿，没有其他因素。

严格自愿

To assert firmly that participation is not required and is based on choice alone.

坚决声明参与不是必需的，并且完全基于自愿。

很大程度上是自愿的

To indicate that something is mostly, but not entirely, based on choice.

表示某事主要但非完全基于自愿。

是自愿的

Used to describe the state of something being optional or done by choice.

用于描述某事是可选择的或出于自愿的状态。

保持自愿

Used to describe something continuing to be optional or based on choice.

用于描述某事继续保持可选或基于选择的状态。