建议信

　　Dear [收信人称呼],I hope this letter finds you well. I am writing to offer some suggestions regarding [主题].As we know, [阐述主题相关现状]. However, there are still some aspects that can be improved. Firstly, [建议一内容]. This is because [阐述建议一的原因]. Secondly, it would be beneficial if [建议二内容]. For instance, [举例说明建议二的好处].

　　I sincerely hope you will find these suggestions useful. Your prompt attention to this matter will be highly appreciated.

　　Best regards,

　　[你的姓名]

　　[日期]

　　投诉信

　　Dear [相关负责人称呼],

　　I am writing to express my dissatisfaction /disappointment/annoyance about [投诉对象].

　　The problem I have encountered is as follows. [详细描述问题，如产品质量问题、服务态度恶劣等]. Not only does it cause inconvenience to me, but also [阐述问题带来的其他负面影响].

　　I strongly demand that you should take immediate actions to solve this problem. For example, [提出解决问题的建议，如退款、换货、改进服务等]. I sincerely hope you can handle this matter properly within [期望解决问题的时间期限].

　　Thank you for your time and I am looking forward to your favorable reply.

　　Yours sincerely,

　　[你的姓名]

　　[日期]

　　邀请信

　　Dear [受邀人称呼],

　　I am extremely pleased to invite you to [活动名称]. It will be held on [活动时间] at [活动地点].

　　This event is going to be remarkable. We have arranged [介绍活动亮点，如精彩的表演、知名嘉宾的出席等]. Also, there will be opportunities for you to [说明活动中可参与的互动环节].

　　I sincerely hope you can come and join us. It will be a great honor for me if you are present. Please let me know your decision as soon as possible.

　　Best wishes,

　　[你的姓名]

　　[日期]