书信（Letter）
书信的格式是：信头（发信人的地址和日期），位于信纸的右上角；信内地址（收信人的地址，私人信件可省去），位于信头下两行左边；称呼，位于信内地址下；正文，位于称呼下，缩进两个字符；署名，位于正文下两行右边；签名，位于结尾下。如：
No.4, Jianguo Rd, Shanghai
May 24th，2003
Dear Sister,
It has been half a year since you left home．I miss you very much.Luckily，I'll come to Guangzhou to attend a meeting on May 10th．The meeting will last five days.I will come to see you during my staying in Guangzhou and we can have a good talk．
I'm looking forward to seeing you!
Yours，
Zhangli
