What will the house of the future look like? Could it have gardens on its walls, or a pool with fish for dinner? Architects believe that they are all possibilities. The only thing for sure is that the houses will be as green as possible. The tree house Many architects in the world would like to build a "tree house." Like a leaf, the surface of the house collects sunlight during the day. The energy can be used to heat water, produce electricity, and even create fresh air for the home. The "root"   of the house is deep under the ground. It uses the soil   to the home's temperature. The Lizard house Like a lizard  , changing color with the weather is the most important design of a lizard house. When it's in the bright sun, the cover of the house will turn dark to protect it from strong heat. During dark days, it turns white and takes in as much light and heat as possible to produce energy. Meals at home This design is perhaps as much about the future of food production as architecture  . It has gardens on the outside wall of the house. People can plant tomatoes, carrots and green tea on them. So every day in the morning, you just need to walk outside and collect your meals. Learning from the past Looking to the future isn't the only way to be green. Sometimes, ancient techniques   can also help cut down energy use. For example, a chimney   can be a useful air conditioner because it is easier of hot air to flow out at the chimney. ,A, B, C, D. What will happen to the cover of the lizard house when it's in the bright sun?
It will take in light. It will produce energy. It will turn dark. It will turn white.