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NEW MATERIAL CAN COOL BUILDINGS Researchers at Stanford University have developed a new material that can move heat out of buildings and into space. 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. However, instead of turning sunlight into energy as solar panels do, the material turns heat into infrared 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 also act like a mirror. They take heat out of buildings and reflect the light from the sun. Both the heat and sunlight are sent 100 kilometers into outer space. The panels are cool to the touch, even in the sun. Researchers say they can reduce the indoor temperature to nearly 5 degrees Celsius below the temperature outside. Mr. Fan says it is like having a window into space. He says the heat is sent directly into space without warming the air. Buildings in developing countries that do not have electricity or air conditioning could use the panels.In areas where one is off-grid,there is a significant 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 Stanford researchers described their technology in the science publication _Nature_. They say the main problem is creating actual cooling systems using the high-tech panels. It may be possible to develop a cooling spray technology in the next three to five years that could be used on existing solid structures. 1. The material can cool buildings only on cold days.{T; F} 2. The material turns heat intoinfrared radiation because it is a very thick sheet with many layers that could be placed on a roof like solar panels.{T; F} 3. The heat of the buildings and sunlight are sent 100 kilometers into outer space by the panels.{T; F} 4. The off-grid areas may use the panels to reduce the temperature of buildings to store medicine or even food.{T; F} 5. A cooling spray technology may be developed in the near future that could be used on existing solid structures.{T; F}
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【单选题】尼康半画幅相机上安装50mm镜头,等效焦距为( )
A.
65
B.
75
C.
80
D.
100
【单选题】若数列{a n }是公比为4的等比数列,且a 1 =2,则数列{log 2 a n }是(  )
A.
公差为2的等差数列
B.
公差为lg2的等差数列
C.
公比为2的等比数列
D.
公比为lg2的等比数列
【单选题】下面关于指针的运算中,描述( )是错误的。
A.
两个指针在一定条件下可以进行相等或者不等的运算
B.
可以用一个空指针赋给某个指针
C.
两个指针在一定的条件下可以相减
D.
两个指针在一定的条件下可以相加
【单选题】下列关于指针的操作中,错误的是( )。
A.
基类型不同的指针不可以进行比较运算
B.
可以用一个空指针赋给某个指针
C.
一个指针可以加上两个整数之差
D.
两个同类型的指针可以相加
【单选题】下面关于指针的运算中,描述( )是不正确的。
A.
两个指针在一定条件下可以进行相等或者不等的运算
B.
可以用一个空指针赋给某个指针
C.
两个指针在一定条件下可以相减
D.
两个指针在一定条件下可以相加
【单选题】下列关于指针的操作中,错误的是
A.
两个同类型的指针可以进行比较运算
B.
可以用一个空指针赋给某个指针
C.
一个指针可以加上两个整数之差
D.
两个同类型的指针可以相加
【简答题】等差数列{a n }是递增数列,前n项和为S n ,且a 1 ,a 3 ,a 9 成等比数列,S 5 =a 5 2 , (1)求数列{a n }的通项公式; (2)若数列{b n }满足b n = ,求数列{b n }的前99项的和.
【单选题】某患者金属冠左下 6 约 1 年,现因口腔异味再次就诊。口腔检查发现:左下 6 颊侧龈缘处有大量食物残渣,局部牙龈有萎缩现象。造成这种结果的原因可能是
A.
邻面突度过大
B.
轴面突度过大
C.
轴面突度过小
D.
邻面突度过小
【判断题】系统经历任一可逆过程的熵变一定为零
A.
正确
B.
错误
【简答题】已知数列{a n }首项a 1 =2,且对任意n∈N*,都有a n+1 =ba n +c,其中b,c是常数. (1)若数列{a n }是等差数列,且c=2,求数列{a n }的通项公式; (2)若数列{a n }是等比数列,且|b|<1,当从数列{a n }中任意取出相邻的三项,按某种顺序排列成等差数列,求使{a n }的前n项和S n < 成立的n取值集合.
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