Mr. Smith has two children. One is a son called Sam, the other is a daughter called Sally. Sam is eleven years old. He studies at school. Sally is four years old. She is too young to go to school.
One evening Sam is doing his homework. Sally is sitting at the desk and writing something on a piece(张；片）of paper(纸）in front of her.
"What are you doing, Sally?" asks Sam.
"I'm writing a letter to my friend, Rose," answers Sally.
"How can you?" Sam says in surprise(吃惊）, "You can't write, you know."
"It doesn't mater(没关系）," Sally says, "Rose says, Rose is four, too. She can't read, either(也)."
