r. out of your own free will
adv. 自愿地, 以自由意志
1. She decided to help the charity voluntarily.
她决定自愿帮助这个慈善机构。
2. He voluntarily joined the team to assist with the project.
他自愿加入团队来协助这个项目。
3. Many people volunteered their time to clean up the park.
许多人自愿花时间来清理公园。