我写这封信的目的是告诉您，我已经被国际奥委会聘为2016年奥运会见习记者。
I am writing this letter to tell you that I have been recruited by the International Olympic Committee as the trainee reporter for the 2016 Olympic Games.
我写这封信的目的是提出一些有益的建议来提升您的服务质量。
I am writing the letter in purpose of offering some conducive recommendations to upgrade the quality of your service.
我们写这封信的目的是告知贵方，迄今我方没有收到贵方有关我方5月25日订购货物的答复。
We are writing this letter to tell you that up to now news has come from you about the goods we ordered on May 25th.
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