With regards to ( 1 ), I , as a 身份2，am writing this letter in the aim of 3doing sth.
求职信：1hunting job 2：graduate 3：applying for the job
投诉信：1：your service/products 2:customer 3:complaining sth
建议信：1：my suggestion about sth 2:fair-minded citizen/adolescent
3:putting forward proposal of sth
邀请信： 1： activity of academy /getting recreation
2:one of the people admiring you to the fullest(崇拜你的人之一)
或者 your best friend
3:inviting you to do sth
咨询信：with regards to sth , I ,as a graduate from the department of economic , am writing this letter in the aim of /on the purpose of —gaining some detailed information about ……
with regards to sth I always want to but fail to tell you, i , as your best friend, am writing this letter/Missive in the aim of expressing my heartfelt (gratitude/apology/congratulations)due to the fact that 表达感情的原因事件。
Hosts of shortcoming as I have, but I am still applying for the position for the reason below.
Plenty of valuable experience as the position has brought me, but I had better resign/leave the position for the reason below.
Precious and tight as your time is, but we ,to be honest,still desire your presence/attendance.
What I have been reflecting on is sth
What I have been reflecting on is the fact that
frankly speaking 诚实说
To tell the truth
Your prompt attention to my letter will be highly appreciated.
I am looking forward to your favorable reply at your earliest convenience.
Words fail me when I want to express my sincere gratitude/apology to you.
I take the opportunity to manifest my heartfelt appreciation/sorry to the the kind assistance you rendered me./to the inconvenience I have caused.
Please do not hesitate to contact me if there is any further questions.