dear xx: it's the most wonderful friday i have ever spent .now i want to share my happiness with you . i play a role in()activity,+活动介绍(it'a activity that...)+我学到了什么(what i learnt is.) i really enjoy it,though time is short ,i still satified with what i have learn.i hope you also can have a chance to take part in the activity like that. 大致格式就是这样啦···因为不知道你要求写什么活动什么内容.自己补补吧~