What is the sky(天空)? Where is it? How high is it? What lies above it? These questions are hard to answer, aren’t they?
Is the sky blue? The sky has no color. We know that there is air around the world. When planes fly, they need air to lift their wings(翼) . Planes cannot fly very high because when they go high, the air gets thinner. If we go up about 1,200 kilometers from the earth, we find there is no air.
Perhaps(也许) we can answer some of our questions now. The sky is space(空间). In this space there is only the sun, the moon and all the stars.
6.What is the sky?
A. It’s the clouds       B. It’s space.     C It’s air      D It’s nothing
7. The sky _____
A. is blue        B. is white        C. is black     D. has no color
8. Planes cannot fly very high because _________.
A. the air becomes thinner                         B. the flying machine is not good       
C. people will be afraid if the planes fly too high      D. it is not necessary for planes to fly so high
9 If we go up about 1,200 kilometers from the earth, we find ___________.
A. there is more air   B. there is less air   C .there is nothing but air   D there is no air
10. In space there is _________.
A. nothing       B. air everywhere       C. everything       D. only the sun , the moon and all the stars

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” (根) of the house is deep under the ground. It uses the soil (土壤) to the home’s temperature.
The Lizard house
Like a lizard (蜥蜴), 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 (建筑风格). 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 (古老的技术) can also help cut down energy use. For example, a chimney (烟囱) can be a useful air conditioner because it is easier of hot air to flow out at the chimney.
【小题1】What is the best title (标题) of the passage?
A. Green house of the future.
b. The greener, the better.
C. How to build green houses.
D. Changes of the houses.
【小题2】We can heat water, produce electricity or create fresh air for the home            .
A. with the root of a leaf.
b. with the energy from sunlight.
C. with the soil under the ground
D. with gardens on its walls.
【小题3】What will happen to the cover of the lizard house when it’s in the bright sun?
A. It will take in light.
b. It will produce energy.
C. It will turn dark.
D. It will turn white.
【小题4】The passage seems to tell us that meals at home in the future            .
A. will be more delicious.
b. need more cooks.
C. cost as much as possible.
D. will be greener.
【小题5】A chimney can be a useful air conditioner but it used to cause          .
A. pollution.   b. accident.     C. noise.      D. techniques.