每位完成马拉松的参与者将获得证书。

Each ___participant who completes the marathon will get a certificate.

她是社区服务项目的积极参与者。

She was an active ___participant in the community service project.

会议吸引了来自不同国家的一百多位参与者。

The conference attracted over a hundred ___participants from various countries.