假设你暑假参加了你所在社区组织的义工(volunteer)活动。请给你的美国朋友Tom写一封英文电子邮件，与他分享你的感想。内容包括:1.你做了什么义工工作?2.你认为做义工的意义是什么?3.请以Li Ke.署名。

         I have been a volunteer in 2010 Shanghai EXPO,it was really an unforgettable

experience.Although volunteer's work was hard and tired I still feel very happy cause it offers me a good opportunity to help visitors from foreign counties thus can practice my oral English.I also enhance my sense of reasonability during volunteer work.I worked with other volunteers as a team,together we solved different problems,we also became good friends after EXPO.I was proud of myself and surely I will treasure this experience.

        Yours Li Ke