书面表达。
下面是一个中学生给某报编辑部写的一封信，仔细阅读并就信的内容以编辑 (Jack) 的名义给此
中学生回一封信。
Dear editor,
I am an active girl, and I speak and laugh loudly in the classroom, like a boy. I don't care about small
matters. On the contrary, my neighbor, the girl who sits next to me, speaks quietly and dare not do the
things I often do. I can understand this.
What I can't stand is that she often gets angry with me about small things. How can I get along with
her？
Yours,
Sunny
【注意】1. 书信格式要规范；
2. 回信需就原信内容给出至少三条建议（如谈心、相互理解、参加他们的生日等活动，
谈论共同话题，分享快乐等等）；
3. 不要逐字翻译，可适当补充；
4. 字数：120左右。
，利用课本中推导等差数列前n项和的公式的方法，可求得f(-12)+f(-11)+f(-10)+…+f(0)+…+f(11)+f(12)+f(13)的值为（）．