阅读短文，回答问题
Jimmy is happy. His uncle gives him a nice red pen. He likes it very much. He takes it to school and shows it to his best friend Jack as soon as he gets to school. Jack likes it, too.
After the math class, Jimmy opens his pencil box and wants to show the pen to other classmates. But it's not there. "Where is my pen?" Jimmy thinks, and he starts to look for it in his schoolbag. He can't find it. The red pen is lost. Jimmy is sad. He remembers he only shows the pen to Jack.
"Jack, I can't find my pen," Jimmy says to his friend.
After hearing this, Jack looks uneasy(不安的).
"You will find it," he says.
Jimmy says nothing and doesn't tell others about this.
In the afternoon, Jimmy takes out his science book before the science class. He finds his red pen is in it. A card is in the book, too. It says, "Here's your pen and I'm really sorry. Are we still best friends?"
"Sure," Jimmy thinks and gives a big smile(微笑) to Jack.