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Putting Plants to Work

Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They’ve been using sunlight as an energy source for billions of years.
Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you’re a plant, it’s difficult and expensive to convert sunlight into storable energy. That’s why scientists are taking a closer look at exactly how plants do it.
Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo., is working with green algae. She’s trying to trick
A. Plants are the real experts in producing solar energy.
B. Plants have been used to produce solar energy.
C. Plants have been using solar energy for billions of years.
D. Plants have been a source of solar energy.

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Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They’ve been using sunlight as an energy source for billions of years.
Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you’re a plant, it’s difficult and expensive to convert sunlight into storable energy. That’s why scientists are taking a closer look at exactly how plants do it.
Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo., is working with green algae. She’s trying to trick
A. Because they want algae to produce sugars and starches.
B. Because they want green plants to become a new source of energy.
C. Because they want to turn plant sugars to a new form of energy.
D. Because they want to make photosynthesis more efficient.

[单项选择]第二篇Putting Plants to Work Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They’ve been using sunlight as an energy source for billions of years. Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you’re a plant, it’s difficult and expensive to convert sunlight into storable energy. That’s why scientists are taking a closer look at exactly how plants do it. Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in Golden, Colo., is working with green algae. She’s trying to trick them into producing hydrogen instead of sugars when
A. They are the real experts in producing it.
B. They have been a source of it.
C. They have been used to produce it.
D. They have been using it for billions of years.

[单项选择]The price of electricity produced using wind power is A. lower than the price of electricity produced using coal. B. expected to fall below that of electricity produced using coal. C. expected to fall to a level closer to that of electricity produced using coal.

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