đáp án đọc tiếng anh 6 en40 full ehou

ĐỌC - TIẾNG ANH 6 - EN40.033
1. Choose the most suitable headings for the paragraph. An intellectual
breakthrough, brilliant though it may be, does not automatically ensure that
the transition is made from theory to practice. Despite the fact that rockets had
been used sporadically for several hundred years, they remained a relatively
minor artefact of civilisation until the twentieth century. Prodigious efforts,
accelerated during two world wars, were required before the technology of
primitive rocketry could be translated into the reality of sophisticated
astronauts. It is strange that the rocket was generally ignored by writers of
fiction to transport their heroes to mysterious realms beyond the Earth, even
though it had been commonly used in fireworks displays in China since the
thirteenth century. The reason is that nobody associated the reaction principle
with the idea of travelling through space to a neighbouring world.
The impact of the reaction principle
► How the reaction principle
The first use of steam
Writers’ theories of the reaction principle
2. Choose the most suitable headings for the paragraph. The concept of the
rocket, or rather the mechanism behind the idea of propelling an object into
the air, has been around for well over two thousand years. However, it wasn’t
until the discovery of the reaction principle, which was the key to space travel
and so represents one of the great milestones in the history of scientific thought,
that rocket technology was able to develop. Not only did it solve a problem that
had intrigued man for ages, but, more importantly, it literally opened the door
to exploration of the universe.
► The impact of the reaction principle
Writers’ theories of the reaction principle
How the reaction principle
The first use of steam

1|Page

3. In paragraphs A to D the author describes four processes which may
contribute to the extinction of a species. Match the process to the suitable
paragraph.A Early attempts to predict population viability were based on
demographic uncertainty Whether an individual survives from one year to the
next will largely be a matter of chance. Some pairs may produce several young
in a single year while others may produce none in that same year. Small
populations will fluctuate enormously because of the random nature of birth
and death and these chance fluctuations can cause species extinctions even if,
on average, the population size should increase. Taking only this uncertainty of
ability to reproduce into account, extinction is unlikely if the number of
individuals in a population is above about 50 and the population is growing.B
Small populations cannot avoid a certain amount of inbreeding. This is
particularly true if there is a very small number of one sex. For example, if
there are only 20 individuals of a species and only one is a male, all future
individuals in the species must be descended from that one male. For most
animal species such individuals are less likely to survive and reproduce.
Inbreeding increases the chance of extinction.C Variation within a species is the
raw material upon which natural selection acts. Without genetic variability a
species lacks the capacity to evolve and cannot adapt to changes in its
environment or to new predators and new diseases. The loss of genetic diversity
associated with reductions in population size will contribute to the likelihood of
extinction.D Recent research has shown that other factors need to be
considered. Australia’s environment fluctuates enormously from year to year.
These fluctuations add yet another degree of uncertainty to the survival of
many species. Catastrophes such as fire, flood, drought or epidemic may reduce
population sizes to a small fraction of their average level. When allowance is
made for these two additional elements of uncertainty the population size
necessary to be confident of persistence for a few hundred years may increase

to several thousand. An imblance of the sexes.
► Paragraph B
Paragraph D
Paragraph C
Paragraph A

2|Page


4. In paragraphs A to D the author describes four processes which may
contribute to the extinction of a species. Match the process to the suitable
paragraph.A Early attempts to predict population viability were based on
demographic uncertainty Whether an individual survives from one year to the
next will largely be a matter of chance. Some pairs may produce several young
in a single year while others may produce none in that same year. Small
populations will fluctuate enormously because of the random nature of birth
and death and these chance fluctuations can cause species extinctions even if,
on average, the population size should increase. Taking only this uncertainty of
ability to reproduce into account, extinction is unlikely if the number of
individuals in a population is above about 50 and the population is growing.B
Small populations cannot avoid a certain amount of inbreeding. This is
particularly true if there is a very small number of one sex. For example, if
there are only 20 individuals of a species and only one is a male, all future
individuals in the species must be descended from that one male. For most
animal species such individuals are less likely to survive and reproduce.
Inbreeding increases the chance of extinction.C Variation within a species is the
raw material upon which natural selection acts. Without genetic variability a
species lacks the capacity to evolve and cannot adapt to changes in its
environment or to new predators and new diseases. The loss of genetic diversity
associated with reductions in population size will contribute to the likelihood of

extinction.D Recent research has shown that other factors need to be
considered. Australia’s environment fluctuates enormously from year to year.
These fluctuations add yet another degree of uncertainty to the survival of
many species. Catastrophes such as fire, flood, drought or epidemic may reduce
population sizes to a small fraction of their average level. When allowance is
made for these two additional elements of uncertainty the population size
necessary to be confident of persistence for a few hundred years may increase
to several thousand. Loss of ability to adapt.
► Paragraph C
Paragraph B
Paragraph A
Paragraph D

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5. (**) In paragraphs A to D the author describes four processes which may
contribute to the extinction of a species. Match the process to the suitable
paragraph. A, Early attempts to predict population viability were based on
demographic uncertainty Whether an individual survives from one year to the
next will largely be a matter of chance. Some pairs may produce several young
in a single year while others may produce none in that same year. Small
populations will fluctuate enormously because of the random nature of birth
and death and these chance fluctuations can cause species extinctions even if,
on average, the population size should increase. Taking only this uncertainty of
ability to reproduce into account, extinction is unlikely if the number of
individuals in a population is above about 50 and the population is growing. B,
Small populations cannot avoid a certain amount of inbreeding. This is
particularly true if there is a very small number of one sex. For example, if
there are only 20 individuals of a species and only one is a male, all future

individuals in the species must be descended from that one male. For most
animal species such individuals are less likely to survive and reproduce.
Inbreeding increases the chance of extinction. C, Variation within a species is
the raw material upon which natural selection acts. Without genetic variability
a species lacks the capacity to evolve and cannot adapt to changes in its
environment or to new predators and new diseases. The loss of genetic diversity
associated with reductions in population size will contribute to the likelihood of
extinction. D, Recent research has shown that other factors need to be
considered. Australia’s environment fluctuates enormously from year to year.
These fluctuations add yet another degree of uncertainty to the survival of
many species. Catastrophes such as fire, flood, drought or epidemic may reduce
population sizes to a small fraction of their average level. When allowance is
made for these two additional elements of uncertainty the population size
necessary to be confident of persistence for a few hundred years may increase
to several thousand. Natural disasters.
► Paragraph D
Paragraph A
Paragraph C
Paragraph B

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6. In paragraphs A to D the author describes four processes which may
contribute to the extinction of a species. Match the process to the suitable
paragraph. A Early attempts to predict population viability were based on
demographic uncertainty Whether an individual survives from one year to the
next will largely be a matter of chance. Some pairs may produce several young
in a single year while others may produce none in that same year. Small
populations will fluctuate enormously because of the random nature of birth

and death and these chance fluctuations can cause species extinctions even if,
on average, the population size should increase. Taking only this uncertainty of
ability to reproduce into account, extinction is unlikely if the number of
individuals in a population is above about 50 and the population is growing.B
Small populations cannot avoid a certain amount of inbreeding. This is
particularly true if there is a very small number of one sex. For example, if
there are only 20 individuals of a species and only one is a male, all future
individuals in the species must be descended from that one male. For most
animal species such individuals are less likely to survive and reproduce.
Inbreeding increases the chance of extinction.C Variation within a species is the
raw material upon which natural selection acts. Without genetic variability a
species lacks the capacity to evolve and cannot adapt to changes in its
environment or to new predators and new diseases. The loss of genetic diversity
associated with reductions in population size will contribute to the likelihood of
extinction.D Recent research has shown that other factors need to be
considered. Australia’s environment fluctuates enormously from year to year.
These fluctuations add yet another degree of uncertainty to the survival of
many species. Catastrophes such as fire, flood, drought or epidemic may reduce
population sizes to a small fraction of their average level. When allowance is
made for these two additional elements of uncertainty the population size
necessary to be confident of persistence for a few hundred years may increase
to several thousand.The haphazard nature of reproduction.
► Paragraph A
Paragraph D
Paragraph C
Paragraph B

5|Page

7. Read the text and choose the best answer. De Vany's advice to the modern
exercise freak is to cut duration and frequency, and increase intensity. 'Our
muscle fibre composition reveals that we are adapted to extreme intensity of
effort,' says De Vany, a professor of economics at the Institute of Mathematical
Behavioral Sciences at the University of California, Irvine. His approach to
fitness combines Darwinian thinking with his interest in chaos theory and
complex systems.
In the paragraph, De Vany recommends that people
should….
► exercise harder but for less time.
learn more about how the human body reacts to exercise.
give their muscles more time to recover from exercise.
exercise less frequently.
8. Read the text and choose the best answer. De Vany's advice to the modern
exercise freak is to cut duration and frequency, and increase intensity. 'Our
muscle fibre composition reveals that we are adapted to extreme intensity of
effort,' says De Vany, a professor of economics at the Institute of Mathematical
Behavioral Sciences at the University of California, Irvine. His approach to
fitness combines Darwinian thinking with his interest in chaos theory and
complex systems.
In the paragraph, De Vany recommends that people
should….
► exercise harder but for less time.
exercise less frequently.
give their muscles more time to recover from exercise.
learn more about how the human body reacts to exercise.

6|Page

9. Read the text and choose the best answer. These stories of killer bees in the
news in recent years have attracted a lot of attention as bees have made their
way from South America to North America. Killer bees are reputed to be
extremely aggressive in nature, although experts say that their aggression may
have been somewhatinflated. The killer bee is a hybrid—or combination- of the
very mild European strain of honeybee and the considerably more aggressive
African bee, which was created when African strain was imported into Brazil
in 1955. The African bees were brought into Brazil because their aggression
was considered an advantage: they were far more productive than their
European counterparts in that they spent a higher percentage of their time
working and continued working longer in inclement weather than did the
European bees. These killer bees have been known to attack humans and
animals, and some fatalities have occurred. Experts point out, however, that the
mixed breed known as the killer bee is actually not at all as aggressive as the
pure African bee. They also point out that the attacks have a chemical cause. A
killer bee stings only when it has been disturbed; it is not aggressive by nature.
However, after a disturbed bee stings and flies away, it leaves its stinger
embedded in the victim. In the vicera attached to the embedded stinger is the
chemical isoamyl acetate, which has an odor that attracts other bees. As other
bees approach the victim of the original sting, the victim tends to panic, thus
disturbing other bees and causing them to sting. The new sting create more of
the chemical isoamyl acetate, which attracts more bees and increases the panic
level of the victim. Killer bees tend to travel in largeclusteror swarms and thus
respond in large numbers to the production of isoamyl acetate. A “hybrid" in
paragraph 2 is
an enemy
► a mixture
a predecessor
a relative

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10. Read the text and choose the best answer.‘People still tell me, “Children
don’t read nowadays”,’ says David Almond, the award-winning author of
children’s books such as Skellig. The truth is that they are skilled, creative
readers. When I do classroom visits, they ask me very sophisticated questions
about use of language, story structure, chapters and dialogue.’ No one is
denying that books are competing with other forms of entertainment for
children’s attention but it seems as though children find a special kind of
mental nourishment within the printed page.What is the main idea of this
paragraph?
► the fact that children are able to identify and discuss the important elements of
fiction
Children will read many books by an author that they like.
Children are quick to decide whether they like or dislike a book
the undervaluing of children’s society
11. Read the text and choose the best answer.‘The dingo started out as a quiet
observer,’ writes Roland Breckwoldt, in A Very Elegant Animal: The Dingo,
‘but soon came to represent everything that was dark and dangerous on the
continent.’ It is estimated that since sheep arrived in Australia, dingo numbers
have increased a hundredfold. Though dingoes have been eradicated from
parts of Australia, an educated guess puts the population at more than a
million.Eventually government officials and graziers agreed that one wellmaintained fence, placed on the outer rim of sheep country and paid for by
taxes levied on woolgrowers, should supplant the maze of private netting. By
1960, three states joined their barriers to form a single dog fence.Dingoes have
flourished as a result of the sheep industry.
► TRUE
FALSE
NOT GIVEN

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12. Read the text and choose the best answer.A few years ago, publishers lost
confidence and wanted to make books more like television, the medium that
frightened them most,’ says children’s book critic Julia Eccleshare. ‘But books
aren’t TV, and you will find that children always say that the good thing about
books is that you can see them in your head. Children are demanding readers,’
she says. ‘If they don’t get it in two pages, they’ll drop it.’No more are
children’s authors considered mere sentimentalists or failed adult writers.
'Some feted adult writers would kill for the sales,’ says Almond, who sold
42,392 copies of Skellig in 1999 alone. And advances seem to be growing too:
UK publishing outfit Orion recently negotiated a six-figure sum from US
company Scholastic for The Seeing Stone, a children's novel by Kevin CrossleyHolland, the majority of which will go to the author.Which company has just
invested heavily in an unpublished children’s book?
► Orion
Skellig
Kevin Crossley-Holland
Almond

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13. (**) Read the text and choose the best answer.A stumbling blockHowever,
there is still a big stumbling block. The laser is no nifty portable: it’s a monster
that takes up a whole room. Diels is trying to cut down the size and says that a
laser around the size of a small table is in the offing. He plans to test this more
manageable system on live thunderclouds next summer.Bernstein says that
Diels’s system is attracting lots of interest from the power companies. But they

have not yet come up with the $5 million that EPRI says will be needed to
develop a commercial system, by making the lasers yet smaller and cheaper. ‘I
cannot say I have money yet, but I’m working on it,’ says Bernstein. He
reckons that the forthcoming field tests will be the turning point - and he’s
hoping for good news. Bernstein predicts ‘an avalanche of interest and support’
if all goes well. He expects to see cloud-zappers eventually costing $50,000 to
$100,000 each.Other scientists could also benefit. With a lightning ‘switch’ at
their fingertips, materials scientists could find out what happens when mighty
currents meet matter. Diels also hopes to see the birth of ‘interactive
meteorology’ - not just forecasting the weather but controlling it. ‘If we could
discharge clouds, we might affect the weather,’ he says.And perhaps, says Diels,
we’ll be able to confront some other meteorological menaces. ‘We think we
could prevent hail by inducing lightning,’ he says. Thunder, the shock wave
that comes from a lightning flash, is thought to be the trigger for the torrential
rain that is typical of storms. A laser thunder factory could shake the moisture
out of clouds, perhaps preventing the formation of the giant hailstones that
threaten crops. With luck, as the storm clouds gather this winter, laser-toting
researchers could, for the first time, strike back.Obtaining money to improve
the lasers will depend on tests in real storms.
► TRUE
FALSE
NOT GIVEN

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14. (**) Read the text and choose the best answer.A stumbling blockHowever,
there is still a big stumbling block. The laser is no nifty portable: it’s a monster
that takes up a whole room. Diels is trying to cut down the size and says that a
laser around the size of a small table is in the offing. He plans to test this more

manageable system on live thunderclouds next summer.Bernstein says that
Diels’s system is attracting lots of interest from the power companies. But they
have not yet come up with the $5 million that EPRI says will be needed to
develop a commercial system, by making the lasers yet smaller and cheaper. ‘I
cannot say I have money yet, but I’m working on it,’ says Bernstein. He
reckons that the forthcoming field tests will be the turning point - and he’s
hoping for good news. Bernstein predicts ‘an avalanche of interest and support’
if all goes well. He expects to see cloud-zappers eventually costing $50,000 to
$100,000 each.Other scientists could also benefit. With a lightning ‘switch’ at
their fingertips, materials scientists could find out what happens when mighty
currents meet matter. Diels also hopes to see the birth of ‘interactive
meteorology’ - not just forecasting the weather but controlling it. ‘If we could
discharge clouds, we might affect the weather,’ he says.And perhaps, says Diels,
we’ll be able to confront some other meteorological menaces. ‘We think we
could prevent hail by inducing lightning,’ he says. Thunder, the shock wave
that comes from a lightning flash, is thought to be the trigger for the torrential
rain that is typical of storms. A laser thunder factory could shake the moisture
out of clouds, perhaps preventing the formation of the giant hailstones that
threaten crops. With luck, as the storm clouds gather this winter, laser-toting
researchers could, for the first time, strike back.The main difficulty associated
with using the laser equipment is related to its………………..
the trigger
interactive meteorology
money
► size

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15. (**) Read the text and choose the best answer.A stumbling blockHowever,

there is still a big stumbling block. The laser is no nifty portable: it’s a monster
that takes up a whole room. Diels is trying to cut down the size and says that a
laser around the size of a small table is in the offing. He plans to test this more
manageable system on live thunderclouds next summer.Bernstein says that
Diels’s system is attracting lots of interest from the power companies. But they
have not yet come up with the $5 million that EPRI says will be needed to
develop a commercial system, by making the lasers yet smaller and cheaper. ‘I
cannot say I have money yet, but I’m working on it,’ says Bernstein. He
reckons that the forthcoming field tests will be the turning point - and he’s
hoping for good news. Bernstein predicts ‘an avalanche of interest and support’
if all goes well. He expects to see cloud-zappers eventually costing $50,000 to
$100,000 each.Other scientists could also benefit. With a lightning ‘switch’ at
their fingertips, materials scientists could find out what happens when mighty
currents meet matter. Diels also hopes to see the birth of ‘interactive
meteorology’ - not just forecasting the weather but controlling it. ‘If we could
discharge clouds, we might affect the weather,’ he says.And perhaps, says Diels,
we’ll be able to confront some other meteorological menaces. ‘We think we
could prevent hail by inducing lightning,’ he says. Thunder, the shock wave
that comes from a lightning flash, is thought to be the trigger for the torrential
rain that is typical of storms. A laser thunder factory could shake the moisture
out of clouds, perhaps preventing the formation of the giant hailstones that
threaten crops. With luck, as the storm clouds gather this winter, laser-toting
researchers could, for the first time, strike back.Weather forecasters are
intensely interested in Diels’s system.
► NOT GIVEN
FALSE
TRUE
16. (**) Read the text and choose the best answer.A war has been going on for
almost a hundred years between the sheep farmers of Australia and the dingo,
Australia’s wild dog. To protect their livelihood, the farmers built a wire fence,

3,307 miles of continuous wire mesh, reaching from the coast of South
Australia all the way to the cotton fields of eastern Queensland, just short of the
Pacific Ocean.Why was the fence built?
to separate the sheep from the cattle
to stop the dingoes from being slaughtered by farmers
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to act as a boundary between properties
► to protect the Australian wool industry
17. (**) Read the text and choose the best answer.Across the Palaeolithic age which covers the period between 2.6 million and 10,000years ago - prey animals
were large, fast on their feet, or both. For men, this would have meant lots of
walking or jogging to find herds, dramatic sprints, jumps and turns, perhaps
violent struggles, and long walks home carrying the kill. Women may not have
had such intense exercise, but they would have spent many hours walking to
sources of water or food, digging up tubers, and carrying children. If modern
hunter-gatherers are anything to go by, men may have hunted for up to four
days a week and travelled 15 kilometres or more on each trip. Women may
have gathered food every two or three days. There would also have been plenty
of other regular physical activities for both sexes such as skinning animals and
tool making, and probably dancing.Our ancestors must have evolved
cardiovascular, metabolic and thermoregulatory systems capable of sustaining
high-level aerobic exertion under the hot African sun, according to Loren
Cordain of the Human Performance Laboratory at Colorado State University.
And given that the Palaeolithic era ended only an evolutionary blink of an eye
ago, we ignore its legacy at our peril. Cordain and his colleagues point out that
in today's developed societies, inactivity is associated with disease.
Contemporary hunter- gatherer societies rarely experience these modern
killers, they say.This is where De Vany's exercise ideas come in. 'The primary
objectives for any exercise and diet programme must be to counter hyperinsulinaemia (chronically elevated insulin) and hypoexertion (wasting of the

body's lean mass through inactivity),' he writes in his forthcoming book about
evolutionary exercise. Exercise and diet are linked. For example, says De Vany,
our appetite control mechanisms work best when our activity mimics that of
our ancestors. But he feels that most modern exercise regimes are not hitting
the mark.Cordain compares modern hunter-gatherer societies to Paleolithic
societies in terms of their…..
healthy mix of work and leisure activities
► resistance to certain fatal illnesses
ability to withstand high temperatures
refusal to change their way of life (Sai)

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18. (**) Read the text and choose the best answer.Art De Vany is 62, but
physical fitness tests three years ago showed he had the body of a 32-year-old.
Although De Vany is sceptical of such assessments, he knows he's in good
shape. His former career as a professional baseball player may have something
to do with it, but he attributes his physical prowess to an, exercise regime
inspired by the lifestyles of our Palaeolithic ancestors.What do you learn about
Art De Vany in the paragraph?
He believes he has inherited a strong body.
► He is older than he appears to be.
He works as a professional sports player.
He frequently tests his health.
19. (**) Read the text and choose the best answer.Avoiding pollution can be a
fulltime job. Try not to inhale traffic fumes; keep away from chemical plants
and building-sites; wear a mask when cycling. It is enough to make you want to
stay at home. But that, according to a growing body of scientific evidence,
would also be a bad idea. Research shows that levels of pollutants such as

hazardous gases, particulate matter and other chemical ‘nasties’ are usually
higher indoors than out, even in the most polluted cities. Since the average
American spends 18 hours indoors for every hour outside, it looks as though
many environmentalists may be attacking the wrong target.In the paragraph
the writer suggests that…….
people should avoid working in cities.
Americans spend too little time outdoors.
► there are several ways to avoid city pollution.
hazardous gases are concentrated in industrial suburbs.

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20. (**) Read the text and choose the best answer.Bad behaviourBut while
rockets are fine for research, they cannot provide the protection from lightning
strikes that everyone is looking for. The rockets cost around $1,200 each, can
only be fired at a limited frequency and their failure rate is about 40 per cent.
And even when they do trigger lightning, things still do not always go according
to plan. ‘Lightning is not perfectly well behaved,’ says Bernstein. ‘Occasionally,
it will take a branch and go someplace it wasn’t supposed to go.’And anyway,
who would want to fire streams of rockets in a populated area? ‘What goes up
must come down,’ points out Jean-Claude Diels of the . Diels is leading a
project, which is backed by EPRI, to try to use lasers to discharge lightning
safely - and safety is a basic requirement since no one wants to put themselves
or their expensive equipment at risk. With around $500,000 invested so far, a
promising system is just emerging from the laboratory.The idea began some 20
years ago, when high-powered lasers were revealing their ability to extract
electrons out of atoms and create ions. If a laser could generate a line of
ionisation in the air all the way up to a storm cloud, this conducting path could
be used to guide lightning to Earth, before the electric field becomes strong

enough to break down the air in an uncontrollable surge. To stop the laser itself
being struck, it would not be pointed straight at the clouds. Instead it would be
directed at a mirror, and from there into the sky. The mirror would be
protected by placing lightning conductors close by. Ideally, the cloud-zapper
(gun) would be cheap enough to be installed around all key power installations,
and portable enough to be taken to international sporting events to beam up at
brewing storm cloudsPower companies have given Diels enough money to
develop his laser.
NOT GIVEN
TRUE
► FALSE

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21. Read the text and choose the best answer.Bees do not see red; thus, flowers
that attract bees tend to be blue, yellow, purple, or other colors. Many bee
attractors also have nectar guides, which are spots near the center1 of each
flower that reflect ultraviolet light, making it easier for the bees to find the
nectar. Bees are also attracted to flowers with a mintlike or sweet smell.
Snapdragons not only attract bees visually, they are adapted to appeal to
certain bee species: snapdragons have a landing platform that, if the bee is the
correct weight, opens—allowing access to the nectar and pollen.Pollinators play
a major role in agriculture. While many staple crops such as rice, corn, canola,
and wheat are self-pollinating or pollinated by the wind, farmers are dependent
on pollinator species for many fruit, vegetable, nut, and seed crops. Over 30
percent of the world’s crops require the work of pollinator species. Bees are the
most common agricultural pollinators, with crops including fruit trees such as
apples and cherries; vegetables such as squash, beans, tomatoes, and eggplant;
flowering shrubs and annual and perennial flowers; forage crops such as clover

and alfalfa; and fiber2 crops such as cotton. Other pollinators include midges
(cocoa), wasps (figs), moths (yucca, papaya), butterflies (asters, daisies,
marigolds), and even a few species of bats (agave, palms, durians) and
hummingbirds (fuchsia).Bees rarely respond to scent.
► FALSE
NOT GIVEN
TRUE

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22. Read the text and choose the best answer.Bees do not see red; thus, flowers
that attract bees tend to be blue, yellow, purple, or other colors. Many bee
attractors also have nectar guides, which are spots near the center1 of each
flower that reflect ultraviolet light, making it easier for the bees to find the
nectar. Bees are also attracted to flowers with a mintlike or sweet smell.
Snapdragons not only attract bees visually, they are adapted to appeal to
certain bee species: snapdragons have a landing platform that, if the bee is the
correct weight, opens—allowing access to the nectar and pollen.Pollinators play
a major role in agriculture. While many staple crops such as rice, corn, canola,
and wheat are self-pollinating or pollinated by the wind, farmers are dependent
on pollinator species for many fruit, vegetable, nut, and seed crops. Over 30
percent of the world’s crops require the work of pollinator species. Bees are the
most common agricultural pollinators, with crops including fruit trees such as
apples and cherries; vegetables such as squash, beans, tomatoes, and eggplant;
flowering shrubs and annual and perennial flowers; forage crops such as clover
and alfalfa; and fiber2 crops such as cotton. Other pollinators include midges
(cocoa), wasps (figs), moths (yucca, papaya), butterflies (asters, daisies,
marigolds), and even a few species of bats (agave, palms, durians) and
hummingbirds (fuchsia).Most grain crops are pollinated by insects.

► FALSE
TRUE
NOT GIVEN

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23. Read the text and choose the best answer.Bees do not see red; thus, flowers
that attract bees tend to be blue, yellow, purple, or other colors. Many bee
attractors also have nectar guides, which are spots near the center1 of each
flower that reflect ultraviolet light, making it easier for the bees to find the
nectar. Bees are also attracted to flowers with a mintlike or sweet smell.
Snapdragons not only attract bees visually, they are adapted to appeal to
certain bee species: snapdragons have a landing platform that, if the bee is the
correct weight, opens—allowing access to the nectar and pollen.Pollinators play
a major role in agriculture. While many staple crops such as rice, corn, canola,
and wheat are self-pollinating or pollinated by the wind, farmers are dependent
on pollinator species for many fruit, vegetable, nut, and seed crops. Over 30
percent of the world’s crops require the work of pollinator species. Bees are the
most common agricultural pollinators, with crops including fruit trees such as
apples and cherries; vegetables such as squash, beans, tomatoes, and eggplant;
flowering shrubs and annual and perennial flowers; forage crops such as clover
and alfalfa; and fiber2 crops such as cotton. Other pollinators include midges
(cocoa), wasps (figs), moths (yucca, papaya), butterflies (asters, daisies,
marigolds), and even a few species of bats (agave, palms, durians) and
hummingbirds (fuchsia).Special markings on a flower help bees to locate the
nectar.
► TRUE
FALSE
NOT GIVEN

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24. Read the text and choose the best answer.Broad-tailed hummingbirds often
nest in quaking aspens, slender deciduous trees with smooth, gray-green bark
found in the Colorado Rockies of the western United States. After flying some
2,000 kilometers north from where they have wintered in Mexico, the
hummingbirds need six weeks to build a nest, incubate their eggs, and raise the
chicks. A second nest is feasible only if the first fails early in the season.
Quality, not quantity, is what counts in hummingbird reproduction.A nest on
the lowest intact branch of an aspen will give a hummingbird a good view, a
clear flight path, and protection for her young. Male hummingbirds claim
feeding territories in open meadows where, from late May through June, they
mate with females coming to feed but take no part in nesting. Thus when the
hen is away to feed, the nest is unguarded. While the smooth bark of the aspen
trunk generally offers a poor grip for the claws of a hungry squirrel or weasel,
aerial attacks, from a hawk, owl, or gray jay, are more likely.The choice of
where to build the nest is based not only on the branch itself but also on what
hangs over it. A crooked deformity in the nest branch, a second, unusually close
branch overhead, or proximity to part of a trunk bowed by a past ice storm are
features that provide shelter and make for an attractive nest site. Scarcely
larger than a halved golf ball, the nest is painstakingly constructed of
spiderwebs and plant down, decorated and camouflaged outside with paperlike bits of aspen bark held together with more strands of spider silk. By early
June it will hold two pea-sized eggs, which each weigh one-seventh of the
mother's weight, and in sixteen to nineteen days, two chicks. According to the
passage, in what circumstances do hummingbirds build a second nest?
► If the eggs are destroyed early in the season
If the winter is unusually warm
If the chicks in the first nest hatch early

If there is an unusually large supply of food

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25. Read the text and choose the best answer.Broad-tailed hummingbirds often
nest in quaking aspens, slender deciduous trees with smooth, gray-green bark
found in the Colorado Rockies of the western United States. After flying some
2,000 kilometers north from where they have wintered in Mexico, the
hummingbirds need six weeks to build a nest, incubate their eggs, and raise the
chicks. A second nest is feasible only if the first fails early in the season.
Quality, not quantity, is what counts in hummingbird reproduction.A nest on
the lowest intact branch of an aspen will give a hummingbird a good view, a
clear flight path, and protection for her young. Male hummingbirds claim
feeding territories in open meadows where, from late May through June, they
mate with females coming to feed but take no part in nesting. Thus when the
hen is away to feed, the nest is unguarded. While the smooth bark of the aspen
trunk generally offers a poor grip for the claws of a hungry squirrel or weasel,
aerial attacks, from a hawk, owl, or gray jay, are more likely.The choice of
where to build the nest is based not only on the branch itself but also on what
hangs over it. A crooked deformity in the nest branch, a second, unusually close
branch overhead, or proximity to part of a trunk bowed by a past ice storm are
features that provide shelter and make for an attractive nest site. Scarcely
larger than a halved golf ball, the nest is painstakingly constructed of
spiderwebs and plant down, decorated and camouflaged outside with paperlike bits of aspen bark held together with more strands of spider silk. By early
June it will hold two pea-sized eggs, which each weigh one-seventh of the
mother's weight, and in sixteen to nineteen days, two chicks. According to the
passage, which of the following is true of the male broad-tailed hummingbird?
► It is not involved in caring for the chicks.
It finds food for the female and the chicks.

It protects the nest while the female searches for food.
It shares nesting duties equally with the female.

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