Question

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 man-made 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 copy this seemingly simple process.

The man-made leaf developed by Daniel Nocera and his partners at MIT can be seen as a special chip 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.

A man-made leaf is not a new idea. The first man-made leaf was invented in 1997 but was too expensive and changeable for practical use. The new leaf, on the contrary, is made of cheap materials, easy to use and highly stable. In laboratory studies, Nocera showed that a man-made leaf prototype (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 change 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 machine 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 enough pure water.

With the goal to “make each home its own power station” and “giving energy to the poor”, scientists believe that the new machine could be widely used in developing countries, especially in India and rural China.

1.What will give power to our house in the future, according to MIT?

A. Man-made leaves.    B. Nuclear.

C. Solar power.    D. Wind.

2.Which of the following orders correctly shows how the man-made leaf is used to produce electricity?

a. man-made leaves split water into hydrogen and oxygen

b. the hydrogen and oxygen gases are stored in a fuel cell

c. the man-made leaves are put in water

d. the fuel cell uses hydrogen and oxygen to produce electricity

A. cbad.    B. bcad.

C. cabd.    D. cadb.

3.What does the underlined “stable” in the 4^th paragraph mean?

A. Secure.    B. Powerful.

C. Unnatural.    D. Unchangeable.

4.The aim of the scientists at MIT in developing the new man-made 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

Answer

1.A

2.C

3.D

4.B

【解析】

本文是一篇说明文。主要介绍了一种未来能给我们提供能源的人造树叶，这种树叶会模仿光合作用把水分解成氢气和氧气，然后再发生反应来发电，可为发展中国家提供便宜的能源。

1.细节理解题。根据第一段最后一句话According to scientists at the Massachusetts Institute of Technology (MIT) in the US, it might be leaves – but man-made ones.可知根据美国麻省理工学院的科学家们的说法，将来会给我们的房子带来能量的是人造树叶，故选A。

2.细节理解题。根据第三段中"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，which uses those two materials to produce electricity，located either on top of a house or beside the house．"当把人造树叶投入一桶水中，它可以把水分解成氢和氧，然后氢和氧气被储存在燃料电池中，燃料电池用这两种气体来产生电能，由此可知正确顺序是cabd，故选C。

3.词义猜测题。The first man-made leaf was invented in 1997 but was too expensive and changeable for practical use. The new leaf, on the contrary, is made of cheap materials, easy to use and highly stable.此处是将新旧人造树叶进行对比，一开始的人造树叶是expensive and changeable（昂贵和多变的），根据句中的on the contrary（正相反），可知新的人造树叶与原来的人造树叶是相反的，新的人造树叶是便宜和不变的（unchangeable.），所以此处stable的意思是Unchangeable，故选D。

4.细节理解题。根据文章最后一段With the goal to “make each home its own power station” and “giving energy to the poor”, scientists believe that the new machine could be widely used in developing countries﹍可知之所以发展新的人造树叶是因为它可为发展中国家提供更便宜的能源，故选B。