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