请找出下列句子中唯一的错误，并改正在后面的横线上。

1. The children is playing football on the grass.  __________________

2. Listen! Who is read English loudly?  __________________

3. What are you doing?  You're writing a letter.  __________________

4. Sandy is siting under the tree.  __________________

5. My brothers are haveing lunch at home now.  __________________