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【简答题】
What will power your house in the future? Nuclear, wind, or solar power? According to scientists at the Massachusetts Institute of Technology (MIT) in the US, it might be leaves –but artificial ones. Natural leaves are able to change sunlight and water into energy. It is known as photosynthesis (光合作用). Now researchers have found a way to imitate this seemingly simple process. The artificial leaf developed by Daniel Nocera and his colleagues at MIT can be seen as a special silicon chip (硅片) with catalysts (催化剂). Similar to natural leaves, it can split water into hydrogen and oxygen when put into a bucket of water. The hydrogen and oxygen gases are then stored in a fuel cell (电池), which uses those two materials to produce electricity, located either on top of a house or beside the house. Though the leaf is only about the shape of a poker card, scientists claimed that it is promising to be an inexpensive source of electricity in developing countries. “One can imagine villages in India and Africa not long from now purchasing an affordable basic power system based on this technology,” said Docera at a conference of the American Chemical Society. An artificial leaf is not a new idea. The first artificial leaf was invented in 1997 but was too expensive and unstable for practical use. The new leaf, by contrast, is made of cheap materials, easy to use and highly stable. In laboratory studies, Nocera showed that an artificial leaf prorotype (原型) could operate continuously for at least 45 hours without a drop in activity. The wonderful improvements come from Nocera’s recent discovery of several powerful new, inexpensive catalysts. These catalysts make the energy transformation (转换) inside the leaf more efficient with water and sunlight. Right now, the new leaf is about 10 times more efficient at carrying out photosynthesis than a natural one. Besides, the device can run in whatever water is available; that is, it doesn’t need pure water. This is important for some countries that don’t have access to pure water. With the goal to “make each home its own power station” and “giving energy to the poor”, scientists believe that the new application could be widely used in developing countries, especially in India and rural China. 小题1:Which of the following order correctly shows how the artificial leaf is used to produce electricity? a. artificial leaves split water into hydrogen and oxygen b. the hydrogen and oxygen gases are stored in a fuel cell c. the artificial leaves are put in water d. the fuel cell uses hydrogen and oxygen to produce electricity A.cbad B.cabd C.bcad D.cadb 小题2:Which of the following statements about new artificial leaves is TRUE according to the article? A.They are inexpensive but unstable. B.They are as efficient at carrying out photosynthesis as natural leaves. C.They can work only in pure water. D.They need several catalysts to help them work efficiently. 小题3:The aim of the scientists at MIT in developing the new artificial leaves is to . A.build-up more power stations in the world B.provide cheaper energy for developing countries C.offer people in developing countries access to pure water D.gain a deeper understanding of the photosynthesis process 小题4:What is the main point of the article? A.Introduction to the history of artificial leaves. B.An invention copying photosynthesis. C.Giving energy to the poor. D.A mixture of water power and solar energy.
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【简答题】设集合A={1,2},={2,3},C={2,3,4},则(A∩B)∪C=______.
【简答题】设a,b,,c满足a+b+c=1,a2+b2+c2=2,a3+b3+c3=3则abc= .
【单选题】设a=-1×(1-2)-3,b=-1-(2-3),c=-[(-1)-(-2)-3],则-a-[-b-(-c)]=(  )
A.
1
B.
0
C.
-1
D.
-2
【多选题】下列说法正确的有:
A.
我国财政支出功能分类主要反映政府活动的不同功能和政策目标。
B.
2017年8月,财政部制定了《支出经济分类科目改革方案》,改革后的支出经济分类包括“政府预算支出经济分类”和“部门预算支出经济分类”。
C.
我国财政支出经济分类主要反映政府支出的经济性质和具体用途。
D.
国际货币基金组织在政府财政统计中,对财政支出的分类有两种方式,一是职能分类,二是经济分类,这也是各国普遍的做法。
【简答题】设 a =(1,-2), b =(-3,4), c =(3,2),则( a +2 b )? c =______.
【单选题】《中华人民共和国民用航空器适航管理条例》中明确规定民用航空器的适航管理由().
A.
民用航空器的设计、制造、使用和维护单位负责
B.
民用航空局负责
C.
航空器营运人和CCAR-145部维修单位负责
D.
民用航空局适航标准司司长负责
【多选题】下列说法正确的有:
A.
我国财政支出功能分类主要反映政府活动的不同功能和政策目标。
B.
国际货币基金组织在政府财政统计中,对财政支出的分类有两种方式,一是职能分类,二是经济分类,这也是各国普遍的做法。
C.
我国财政支出经济分类主要反映政府支出的经济性质和具体用途。
D.
2017 年8月,财政部制定了《支出经济分类科目改革方案》,改革后的支出经济分类包括“政府预算支出经济分类”和“部门预算支出经济分类”。
【简答题】设向量 a ⊥ b ,< a , c >=< b , c >= π 3 且| a |=1,| b |=2,| c |=3,则| a + b + c |=______.
【单选题】民用航空器的适航管理由 ( ) 负责
A.
民航局
B.
民航地区管理局
C.
国务院
D.
中央军委
【判断题】( )滴润眼液是为了缓解配戴隐形眼镜的干燥和不适感。
A.
正确
B.
错误
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