题目内容：

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 4th 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