"Volunteer"的形容词形式是"voluntary",意为"自愿的,志愿的"。这个词可以用来描述那些主动提供帮助、服务或参与某项活动的人或事物,而不是被强制或要求去做的。
例如:
She offers her time to help at the local voluntary organization. (她自愿在当地的组织里帮忙。)
The voluntary work he does for the community is really admirable. (他为社区所做的志愿工作真的很令人钦佩。)
The decision to become a voluntary firefighter was a personal choice. (成为志愿消防员的决定是他个人的选择。)
Voluntary contributions are welcome for the project. (对于这个项目,欢迎自愿捐款。)
在这个例子中,"voluntary"强调了参与是出于个人选择和意愿,而不是被强制或要求的。
总的来说,volunteer的形容词是"voluntary",在句子中,"voluntary"可以用于各种语境,以突出强调某种行为或活动是自愿性质的。