同学你好，该知识点来自沪江网校《BEC商务英语中高级【四项全能实战签约班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学，你好！
标准答案如下：
1.  I am writing to...
2/3.  Further to our previous meeting/ With regard to your letter dated...
4.  how about
5.  I would like to apologize for
6.  I'm sorry that...
7.  we are pleased to
8.  Unfortunately
9.  Can you
10.  Do you want me to
11.  May I remind you...
12.  Don't forget
13.  we look forward to working with you...
14.  See you soon
15.  Yours sincerely

希望能帮到你，祝学习愉快！