17．If a kind of creature lives in an area about 300 metres from the sea surface， .

A．the creature won't have enough food to eat

B．the creature will feel very cold

C．the creature will have to give light by itself

D．the creature will feel too hot

　　Researchers at Stanford University have developed a new material that can move heat out of buildings and into space. The researchers say the material can cool buildings even on hot days. The cooling material is a very thin sheet with many layers that could be placed on a roof like solar panels(板)．However，instead of turning sunlight into energy as solar panels do，the material turns heat into radiation.

　　Shanhui Fan is an electrical engineering professor at Stanford University. He says that the panels have a layer of material that is like sand. The panels act like a mirror. They take heat out of buildings and reflect the light from the sun. And he says both the heat and sunlight are sent 100 kilometers into outer space."It's a structure that cools itself without electricity input，even under the sun. So，what it does is basically radiate heat to outer space and also reflect the sunlight so it doesn't get heated up by the sun. Mr Fan says it is like having a window into space. The heat is sent directly into space without warming the air."

　　He says buildings in developing countries that do not have electricity or air conditioning could use the panels."In areas where electricity is out of reach for many people，there is a potential benefit for storing medicine or even food. In many of these situations，being able to reduce the temperature is important. And this would provide a way to do it."

　　The researchers say the main problem is creating actual cooling systems using the high­tech panels. They say it may be possible to develop a cooling spray(喷涂)that could be used on present solid structures. They believe the cooling spray technology could be developed in the next three to five years. They say as much as 15 percent of the energy used in the United States is spent providing power to air conditioning systems.

18．The first paragraph mainly tells us

A．living on hot days is no longer a big problem now

B．a new material is created to cool the buildings