如下图所示的阴影部分是一个长方形，四周是四个正方形，如果这四个正方形的周长的和是240厘米、面积的和是1000平方厘米，那么阴影部分的面积是多少平方厘米？

    The bus stops at the next stop. A mother and her child get on the bus and sit down. The conductor comes to them for the tickets. The mother says. “One ticket to the Children's Park.” The conductor looks at the small child, then says to him, “How old are you, little boy?”

    The mother wants to speak, but the conductor stops her. The boy says, “Mother says I'm four years old at home and two on the bus. ”All the other people laugh.