Volunteering our time to help these people is a good way to spend our free time. 志愿帮助这些人是一种度过我们闲暇时间的好方式。

点拨：Volunteering our time to help these people是动名词短语，在句子中作主语，谓语动词用单数形式。如：

Helping others  (make) me feel happy.