There is/There are

Детская считалочка: There is a mouse in the house. (В доме – мышь) There is a cat in the flat. There is a fox in the box. There is a bee in the tree. Is there a mouse in the house? Is there a cat in the flat? Is there a fox in the box? Is there a bee in the tree? Детская загадка: It's pretty white house. There is no window, There is no door, There is no roof, There is no floor. But there is a pretty yellow ball inside. What is this house? (an egg)