1.last summer/i/provide/English/evening/classes/for/twenty/children.
→Last summer, I provided English evening classes for 20 children.
2.you/volunteer/if/you/help/other/people/willingly/and/without/payment/.
→You will be a volunteer if you help other people willingly and without payment.
3.community service/work /you/do/for/benefits/of/community.
→Community service is work you do for the benefits of the community.