Blue-green algae与green algae是同义词，均指绿藻。

Passage 2
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.
Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.
When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
CarlSagan believes that Venus might be colonized from earth because__________.

A. it might be possible to change its atmosphere
B. its atmosphere is the same as the earth's
C. there is a good supply of water on Venus
D. the days on Venus are long enough

共用题干
第三篇

Preserve the Environment

Throughout history man has changed his physical environment in order to improve his way of life.
With the tools of technology he has altered many physical features of the earth.He has transformed
woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric
power. Man has also modified the face of the earth by draining marshes and cutting through mountains to
build roads and railways.
However,man's changes to the physical environment have not always had beneficial results.Today,
pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons
of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas
and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.
The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor-
mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed.
The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.
Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-
vive on earth.

The ecological balance of the sea is lost when_________.
A:people consume more fish than they used to
B:the ecological balance of the river is lost
C:large numbers of algae,fish and birds are killed
D:the production of marine petroleum is increased

Passage 2
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.
Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.
When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
On Venus there is a lot of__________.

A. water
B. carbon dioxide
C. carbon monoxide
D. oxygen

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."

How do plants relate to solar energy?
A: They have been using it for billions of years.
B: They are the real experts in producing it.
C: They have been a source of it.
D: They have been used to produce it.

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."

Algae are able to use solar energy to produce hydrogen when_______________.
A:they are grown in narrow-necked bottles
B:there is no oxygen in the air
C:there is enough oxygen in the air
D:enough starch is stored

Passage 2
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.
Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.
When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.

CarlSagan believes that Venus might be colonized from earth because__________.
查看材料

A．it might be possible to change its atmosphere
B．its atmosphere is the same as the earth's
C．there is a good supply of water on Venus
D．the days on Venus are long enough

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."

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

Passage 2
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.
Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.
When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
Man can eventually land on Venus only when__________.

A. the algae have done their work
B. the atmosphere becomes cooler
C. there is oxygen
D. it rains there

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."

Scientists study how photosynthesis works because they want to_______________.
A: improve the efficiency of it
B: turn plant sugars to a new form of energy
C: get more sugars and starches from plants
D: make green plants a new source of energy

Algae are plants that can

A.live in very hot temperatures
B.live in very cold temperatures
C.manufacture oxygen
D.all of the above