Grandpa Li is more than seventy years old， and he doesn’t have any son or daughter. He wanted to invite some old people to his house for dinner， but no one can help him. Mingming took his classmates to Grandpa Li’s house when he knows it. They helped Grandpa Li make the bed， do the dishes， sweep the floor， take out the trash and so on. Grandpa Li was very thankful. He asked Mingming and his classmates have supper with them. But they thanked him and then left.