英语翻译我写这封信是想让你知道,我的女儿xxx就读xxx,因亲戚结婚想向你在11.4.14请假共1天.如有什么问题请联络

你要是写信的话很少用hello开头的吧,一般会写一个抬头,然后直接写内容吧我说.
Dear XXX（对方名字）,
I am writing this letter to ask for a day off on Nov.4th,2014 for my daughter, XXX（女儿名字）, who studies XXX since she needs to attend a wedding ceremony of our relative that day.
If you have any question, please contact XXXXXXX.
Best Regards,
XXX（你自己的名字）

Hello,my daughter XXX studies in XXX.I write this letter to tell you that she will take a day off on April 11th,2014 because her relatives get married.If having any questions,you can call me at XXXXXXXX.Hope to get your approval, thank you.

Hello, I write this letter is to want to let you know that my daughter attend XXX, XXX for relatives to get married to you in 11.4.14 leave 1 day.
If you have any questions, please contact XXXXXXXX.
Hope to get your approval, thank you.
就是这样