共用题干第一篇Putting Plants to WorkUsing the power of the sun is nothing new.People have had solar-powered calculators and buildings withsolar panels（太阳能电池板）for decades. But plants are the real experts. They' ve been using sunlight as anenergy source for billions of years.Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide（二氧化 碳）,and water into sugarsand starche（淀粉）,stored energy that the piants can use. This conversion process is called photosynthesis (光合作用）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 very small photosynthesic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in Golden. Cobo.,is working with green algae（水藻）.She's trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficient- ly ,the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthe- sis , plants normally make sugars or strchds. "But under certain conditions,a lot of algae are able to use the sunlight energy not to store starch , but to make hydrogen."Ghirardi says. For example ,algae will produce hy-drogen in an airfree environment. It' s the oxygen in the air that prevents algae from making hydrogen most of the time.Working in an airfree environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate（硫酸盐） from the environment that the algae grow in, they will make hydrogen instead of sugars,even when air is present.Unfortunately, removing the sulfate also makes the algae's cells work very slowly,and not much hydrogen is produced. Still ,the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work,they may be able to speed the cells' activity and produce larger quantities of hydrogen.The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says,and they can grow almost anywhere:"You can grow them in a reactor, in a pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms." Researchers find it difficult to make algae produce hydrogen efficiently because_______________.A:it is hard to create an airfree environmentB:it is expensive to remove the sulfate from the environmentC:removing the sulfate slows down hydrogen productionD:the algae's cells work slowly if there is no oxygen in the air
共用题干
第一篇
Putting Plants to Work
Using the power of the sun is nothing new.People have had solar-powered calculators and buildings with
solar panels（太阳能电池板）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（二氧化
碳）,and water into sugars
and starche（淀粉）,stored energy that the piants can use. This conversion
process is called photosynthesis (光合作用）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 very small
photosynthesic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in
Golden. Cobo.,is working with green algae（水藻）.She's trying to trick them into producing hydrogen
instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficient-
ly ,the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.
The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthe-
sis , plants normally make sugars or strchds. "But under certain conditions,a lot of algae are able to use the
sunlight energy not to store starch , but to make hydrogen."Ghirardi says. For example ,algae will produce hy-
drogen in an airfree environment. It' s the oxygen in the air that prevents algae from making hydrogen most of
the time.
Working in an airfree environment, however, is difficult. It's not a practical way to produce cheap
energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate（硫酸盐）
from the environment that the algae grow in, they will make hydrogen instead of sugars,even when air
is present.
Unfortunately, removing the sulfate also makes the algae's cells work very slowly,and not much
hydrogen is produced. Still ,the researchers see this as a first step in their goal to produce hydrogen efficiently
from algae. With more work,they may be able to speed the cells' activity and produce larger quantities
of hydrogen.
The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to
get and to feed, Ghirardi says,and they can grow almost anywhere:"You can grow them in a reactor, in a
pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms."
第一篇
Putting Plants to Work
Using the power of the sun is nothing new.People have had solar-powered calculators and buildings with
solar panels（太阳能电池板）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（二氧化
碳）,and water into sugars
and starche（淀粉）,stored energy that the piants can use. This conversion
process is called photosynthesis (光合作用）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 very small
photosynthesic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in
Golden. Cobo.,is working with green algae（水藻）.She's trying to trick them into producing hydrogen
instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficient-
ly ,the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.
The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthe-
sis , plants normally make sugars or strchds. "But under certain conditions,a lot of algae are able to use the
sunlight energy not to store starch , but to make hydrogen."Ghirardi says. For example ,algae will produce hy-
drogen in an airfree environment. It' s the oxygen in the air that prevents algae from making hydrogen most of
the time.
Working in an airfree environment, however, is difficult. It's not a practical way to produce cheap
energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate（硫酸盐）
from the environment that the algae grow in, they will make hydrogen instead of sugars,even when air
is present.
Unfortunately, removing the sulfate also makes the algae's cells work very slowly,and not much
hydrogen is produced. Still ,the researchers see this as a first step in their goal to produce hydrogen efficiently
from algae. With more work,they may be able to speed the cells' activity and produce larger quantities
of hydrogen.
The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to
get and to feed, Ghirardi says,and they can grow almost anywhere:"You can grow them in a reactor, in a
pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms."
Researchers find it difficult to make algae produce hydrogen efficiently because_______________.
A:it is hard to create an airfree environment
B:it is expensive to remove the sulfate from the environment
C:removing the sulfate slows down hydrogen production
D:the algae's cells work slowly if there is no oxygen in the air
A:it is hard to create an airfree environment
B:it is expensive to remove the sulfate from the environment
C:removing the sulfate slows down hydrogen production
D:the algae's cells work slowly if there is no oxygen in the air
参考解析
解析：由第一段第三、四句话“But plants are the real experts.They' ye been using sunlight as an energy source for billions of years.”可知答案。
文章的第三段说，科学家企图将植物或植物类生物细胞作为微型光合作用能源供应站 来研究，并举例说，他们正在用绿藻进行实验，若成功，绿藻所产生的氢气将可用来为汽车的燃 料电池充电。所以答案是D。
由文章第四段最后两句“…algae will produce hydrogen in an airfree environment.It' s the oxygen in the air that prevents algae from making hydrogen most of the time.（……绿藻在没有空气 的环境下能产生氢气，是空气中的氧气在阻止绿藻制造氢气。）”可知选B。
A、B都不是正确答案，因为短文的第五段、第六段告诉我们，remove the sulfate和work in an airfree environment都是可能的，但问题是两者都有弊端，使氢气的制造不那么容易。C所 述内容就是困难之一：绿藻细胞因为没有了sulfate而减缓工作速度，因此产生不了多少氢气。 D项与第四段末尾所说的“是空气中的氧气在阻止绿藻制造氢气”矛盾。故选C。
根据最后一段Ghirardi所说的话可知，绿藻可以在任何地方生长，而且用途广泛，联系 此段首句可知Ghirardi所说的意在表示绿藻易于广泛应用，有望成为一种好的能源。故选A。 B项未提到，C项“它们将被到处种植”也不是Ghirardi的话的真正意思，他只是说绿藻易于广 泛种植。D项是对文中“feed”一词所在句的错误理解，feed在此意为“养”。第二篇 文章主要讲的是公共土地在美国能源生产方面的重大作用，分别从产量、税收、未开发的传 统能源、替代能源占全国的份额以及能源开发需求等方面进行了介绍。
文章的第三段说，科学家企图将植物或植物类生物细胞作为微型光合作用能源供应站 来研究，并举例说，他们正在用绿藻进行实验，若成功，绿藻所产生的氢气将可用来为汽车的燃 料电池充电。所以答案是D。
由文章第四段最后两句“…algae will produce hydrogen in an airfree environment.It' s the oxygen in the air that prevents algae from making hydrogen most of the time.（……绿藻在没有空气 的环境下能产生氢气，是空气中的氧气在阻止绿藻制造氢气。）”可知选B。
A、B都不是正确答案，因为短文的第五段、第六段告诉我们，remove the sulfate和work in an airfree environment都是可能的，但问题是两者都有弊端，使氢气的制造不那么容易。C所 述内容就是困难之一：绿藻细胞因为没有了sulfate而减缓工作速度，因此产生不了多少氢气。 D项与第四段末尾所说的“是空气中的氧气在阻止绿藻制造氢气”矛盾。故选C。
根据最后一段Ghirardi所说的话可知，绿藻可以在任何地方生长，而且用途广泛，联系 此段首句可知Ghirardi所说的意在表示绿藻易于广泛应用，有望成为一种好的能源。故选A。 B项未提到，C项“它们将被到处种植”也不是Ghirardi的话的真正意思，他只是说绿藻易于广 泛种植。D项是对文中“feed”一词所在句的错误理解，feed在此意为“养”。第二篇 文章主要讲的是公共土地在美国能源生产方面的重大作用，分别从产量、税收、未开发的传 统能源、替代能源占全国的份额以及能源开发需求等方面进行了介绍。