C

A light emitting diode （发光二极管）, or L．E．D．, is a device that shines when electricity passes through it．But it works differently than traditional kinds of light bulbs．Light emitting diodes use less energy and last much longer than bulbs with a filament （灯丝） inside．L．E．                               D．’s are also cooler to the touch, and shine a lot brighter than they used to．  

Red L．E．D．’s have long been used as signal lights on electronic equipment．But now light emitting diodes also come in blue and other colors．Colored L．E．D．’s are used to show images on everything from wireless phones to huge video signs．And white L．E．D．’s are being used increasingly to replace traditional lighting systems．  

But all these require electricity．In poor countries, people often burn fuel to produce light．But the smoke can make people sick．So an electrical engineering professor from Canada started a project to produce L．E．       D．lighting systems for the developing world．These lights are powered by batteries that can be recharged with energy from the sun．The batteries can also be charged through other ways, such as wind power and water power．

Professor David Irvine-Halliday tells the story of how he got the idea．In 1997, while climbing in the Annapurna mountains in Nepal, he saw a small school．All the children were outside．He looked through a window and saw that inside the school was dark．The school had a sign that read: "We have no teachers．If you want to stay and teach for a few days, we would be very pleased．" Professor Irvine-Halliday says that experience had a big effect on him．Back at the University of Calgary, he was on the Internet one day．He saw a company in Japan selling bright white L．E．                           D．’s．So he built a light with some．This is how he began the Light Up the World Foundation．

48．Compared with traditional kinds of light bulbs, L．E．D．’S________．

A．waste a lot of energy                    B．need shorter time to make

C．shine much brighter                 D．are warmer to touch

49．According to the passage, we know that L．E．D．’s________．

A．will replace all the lights            B．will be more and more popular

C．will be only colored ones               D．will be only used in developing countries

50．According to the passage, we can infer that the purpose of the Light Up the World Foundation is to________．

A．develop L．E．D．lighting system for the developing world                   

B．sell bright white L．E．D．’s

C．collect money for developing countries                                        

D．earn money by selling L．E．D．’s

根据下列句子及所给汉语注释， 在横线上写出空缺处各单词的正确形式。

66．He was employed as a _______(图书管理员) in the company．

67．Have you ________(处理) with the  letters received yesterday?

68．Many economists use the Davos forum as a______(平台) for their financial views．

69．Seeing the scene, he left_______(失望)．

70．There are not enough ____(柜橱)for all the students in the school．

71．He's still______（犹豫） about joining in the expedition．

72．She knitted a pair of_______(手套) herself．

73．It is useful to ____(开发) oil reserves, water power, solar energy because we are badly in need of them．

74．We are busy now and we can’t spare a _______(两周) holiday．

75．Each country celebrates April Fool’s Day_________．(不同)

. —Has the conference about building a water-power plant come to an end?

—No, it’s _______. Experts just disagree on some issues.

         A. under discussion          B. under control                C. under consideration    D. under way

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 (人造的) 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 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，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 Nocera at a conference of the American Chemical Society.

The 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 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 and inexpensive catalysts. These catalysts make the energy transformation 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 “give energy to the poor”，scientists believe that the new technology could be widely used in developing countries，especially in India and rural China.

1.Which of the following orders 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. c，a，b，d                               B．c，b，a，d  

C．b，c，a，d                 D．c，a，d，b

2.The purpose of the scientists at MIT in developing the new artificial leaf 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

3.The main idea of this passage is ________.

A．an introduction to the history of artificial leaves

B．a mixture of water power and solar energy

C．giving energy to the poor

D．an invention copying photosynthesis

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