真正的利他主义者会自愿为社区服务而不求回报。

True ___altruists volunteer for community service without seeking any reward.

这些志愿者是真正的利他主义者，他们放弃周末时间帮助贫困儿童。

These volunteers are true ___altruists, giving up their weekends to help underprivileged children.