voluntary contribution

例句：

1. 1. Many charities rely onvolunteers to contribute their time and skills.
   许多慈善机构依赖志愿者提供时间和技能。
2. 2. The company's decision to donate a portion ofits profits to charity was met with praisefrom the public.
   该公司决定将其部分利润捐赠给慈善机构，这一决定受到了公众的赞扬。
3. 3. The volunteer group organized a fundraisingevent to raise funds for the local community.
   志愿者组织了一次筹款活动，为当地社区筹集资金。