Tom has some new pencils. They are red, black, blue, white and green. Tom likes them very much. He draws(画画) with them. Now he is drawing a house. The door is green. The walls are white. The windows are big, How nice it is! In front (前面) of the house he draws some red flowers. There is a black and white sheep (羊) behind the house. We all like the picture. We say we will put it on (贴) the wall of our classroom. The door of the house is ______.