情景：班里来了一名新同学，学习跟不上。作为班长你要主动帮他补课，放学时，你请同学给父母带一张便条。
任务：请你用英语给父母写一封50左右的便条。告诉他们：

1 为什么今天回家会晚一些； 2 大约补多长时间的课； 3 什么时候到家。    

请用下面格式：
Dear mum and dad ,
  ……
                                                    Bingbing


范文：

Dear mum and dad ,
I’m afraid I have to go home late today , because we have a new classmate . He is very poor in maths and English , so I need to help him to catch up with the class after school . We will stay at school for about an hour . I will get home at about six .
                                                     Bingbing