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  Mr. Smith has an old house. There's a very big tree behind it. In the tree, there's a tree house. It is small, but there're many things in it: a bed, a desk and two chairs. On the desk, there is a computer. Now,Mr. Smith's son, Jack, is in the tree house with his good friend Tom. They like playing computer games very much. Under the tree are the twins, Sally and Molly.

Jack: Hi, Sally and Molly. Please come up and play computer games with us.

Sally: Sorry, we can't. Come down, Jack. I find a wallet under your desk in the classroom.

Jack: What colour is it?

Molly: Black. There's a photo of your family. Look! This is you.

Jack: Yes. That's my wallet.

Molly: Come down and get it. Here you are.

Jack: Thanks.

Molly: You're welcome.