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It is a question that has long puzzled scientists—exactly why are tigers orange? One might think it makes them more obvious-particularly against a leafy green forest background. William Blake summed it up in his famous poem known by generations of schoolchildren: “Tyger, tyger, burning bright / In the forest of the night.” But now the answer is at hand.
While obvious to us, computer simulations (模拟) of what the big cats look to the main animals they hunt for, deer, show a different picture. Humans with normal colour vision, can see red, blue and green colours. But deer can only pick up blue and green light, they are effectively colourblind to the colour red, like some humans. It means the tigers’ orange colouration looks green to them, allowing them to mix perfectly into the background, new research claims.
Dr John Fennell at the University of Bristol and colleagues said that they used computers to estimate how noticeable a given animal was. They did this by using images of the environment in which the animal lives, and then creating images to see whether the camouflage helps the animal to mix in.
Dr Fennell writes that by simulating what the world looks like to animals who are “two-colour vision”—someone who cannot discover the difference between red and green—“we also identify the most suitable colours for hiding and visibility”.
Dr Fennell writes in the Royal Society Journal Inter face: “Considering the coat of a tiger, it has fur that appears orange to a three-colour vision observer rather than some shade of green, though the latter should be more appropriate color for an attack hunter in forests. However, when viewed as a two-colour vision observer, the tiger’s colour is very effective.”
The question then arises as to why tigers don’t grow green coats. Dr Fennell and colleagues write that mammals (哺乳动物) are not able to produce green fur. To do so would “require a significant change to mammalian biochemistry”. There is only one mammal known to have green fur but this is achieved through what might be considered as, well, cheating, not exactly real.
1.Why does the author mention the poem in paragraph 1?
A.To arouse reader s interest in poems.
B.To show the authors respect to the poet.
C.To answer the question of the color of the tiger
D.To stress the noticeable color of the tiger to us.
2.What color is inexistent in the eyes of deer?
A.Black. B.Red.
C.Blue. D.Green.
3.What does the underlined word “camouflage” mean in paragraph 3?
A.The cover of something.
B.The images of something.
C.The way of hiding something.
D.The way of hunting for something.
4.What can be inferred from the last paragraph?
A.The colour of tigers sometimes cheats people.
B.Getting green may prevent tigers from being extinct.
C.There are no mammals with real green fur in the world.
D.The tigers’ fur will probably evolve into green in the future.
高二英语阅读理解中等难度题查看答案及解析
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The predictability of our death rates is something that has long puzzled social scientists. After all, there is no natural reason why 2,500 people should accidentally shoot themselves each year
or why 7,000 should drown or 55,000 die in their cars. No one establishes a quota (定额) for each type of death. It just happens that they follow a consist
ent pattern year after year.A few years ago a Canadian psychologist named Gerald Wilde became interested in this phenomenon. He noticed that mortality rates for violent and accidental deaths throughout
the Western world have remained strangely static throughout the whole of the century, despite all the technological advances and increases in safety standards that have happened in that time. Wilde developed an interesting theory called “risk homeostasis”. According to this theory, people naturally live with a certain level of risk. When something is made safer, people will get around the measure in some way to get back to the original level of danger. If, for instance, they are required to wear seat belts, they will feel safer and thus will drive a little faster and a little more recklessly, thereby statistically canceling out the benefits that the seat belt offers. Other studies have shown that where a crossing is made safer, the accident rate invariably falls there but rises elsewhere along the same stretch of road as if making up for the drop. It appears, then, that we have an inborn need for danger. In all events, it is becoming clearer and clearer to scientists that the factors influencing our lifespan are far more subtle and complex than had been previously thought. It now appears that if you wish to live a long life, it isn’t simply a matter of paying attention to certain precautions such as eating the right foods, not smoking, and driving with care. You must also have the right attitude. Scientists at the Duke University Medical Center made a 15-year study of 500 persons personalities and found, somewhat to their surprise, that people with a suspicious or mistrustful nature die prematurely far more often than people with a sunny disposition. Looking on the bright side, it seems, can add years to your life span.1.What social scientists have long felt puzzled about is why __________.
A. the death rate can not be predicted
B.the death toll remained stable year after year
C.a quota for each type of death has not come into being
D.people lost their lives every year for this or that reason
2.In his research, Gerald Wilde finds that technological advances and increases in safety standards __________.
A.have helped solve the problem of so high death rate
B.have oddly accounted for death rates in the past century
C. have reduced death rates for violent and accidental deaths
D. have achieved no effect in bringing down the number of deaths
3.According to the theory of “risk homeostasis”, some traffic accidents result from ___________.
A. our
inborn desire for riskB. our fast and reckless driving
C. our ignorance of seat belt benefits
D. our instinctive interest in speeding
4.By saying “statistically canceling out the benefits that the seat belt offers” (Para. 2), the author means __________.
A. wearing seat belts does not have any benefits from the statistic point of view
B. deaths from wearing seat belts are the same as those from not wearing them
C. deaths from other reasons counterbalance the benefits of wearing seat belts
D. wearing seat belts does not necessarily reduce d
eaths from traffic accidents5.Which of the following may contribute to a longer life span?
A. Showing adequate trust instead of suspicion of others
B. Eating the food low in fat and driving with great care
C. Cultivating an optimistic personality and never losing heart
D. Looking on the bright side and developing a balanced level of risk
高二英语阅读理解中等难度题查看答案及解析
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IT'S a mystery that has puzzled scientists. Five years ago, researchers found an area in the Atlantic Ocean seabed, where a part of the Earth's outer layer, or crust（地壳）, is missing. A thick layer of dark green rock, which is usually found deep inside the planet, lies exposed.
The crust, mantle(地幔) and core（地核） are the main layers that make up the planet. The mantle rests between the crust and the core.
Last month, a team of 12 British scientists set off on a six-week trip to study the hole in the crust.
The hole is about 4,800 meters below sea level and is believed to be more than 48,000 meters long and more than 48,000 meters wide. Scientists think that there are other nearby gaps. "It is like a window into the interior (内部) of the Earth," says scientist Bramley Murton, who is part of the research team.
The site where the hole is located is part of a ridge (山脉) of undersea volcanoes. There, two of the plates that make up the Earth's surface meet. The plates are always moving. When the plates move away from each other, lava rushes up from the mantle to fill the gap and form a new crust. But this did not happen in the area where the hole is located.
The hole is giving researchers a good opportunity to study what's below the Earth's surface. The team will use a special robotic tool to film the area and get samples of the exposed mantle. They hope to study everything from the chemistry of the oceans to how the Earth's surface behaves under the sea.
1. What's the title for the passage?
A. How to study the earth.
B. The formation of the earth.
C. A hole in the earth.
D. Studying the inside of the earth.
2.For the main layers of the earth, which one is right?
A. crust, mantle, core B. seabed, crust, mantle
C. seabed, mantle, core D. crust, seabed, core
3.How does the hole come into being?
A. It's because of a volcano eruption.
B. It's because of the plates movements
C. It's because lava rushes up from the mantle
D. It's not clear from the passage.
4.By studying the hole, the scientists want to do the following except____.
A. knowing what's below the Earth's surface
B. getting samples of the exposed mantle
C. getting the film of the hole
D. studying the chemistry of the oceans
高二英语阅读理解中等难度题查看答案及解析
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It is exactly ______ we behave ______has changed the world.
A.which; that B.how; that C.how; what D.what; that
高二英语单项填空中等难度题查看答案及解析
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The question that puzzled us is _____ we can get rid of the air pollution in the area.
A．that how
B．how is it that
C．what is it
D．how it is that
高二英语单项填空困难题查看答案及解析
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The question that puzzled them is ____ they can get rid of the air pollution in the area.
A. how is it that B. that is how C. what is that D. how it is that
高二英语单项填空困难题查看答案及解析
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_________ has already been pointed out, grammar is not a set of dead rules.
A. As B. It C. That D. What
高二英语单项填空简单题查看答案及解析
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It is a shopping mall ______has been built in ______ used to be a school.
A. which; where B. that; what C. which; that D. that; where
高二英语单项填空中等难度题查看答案及解析
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The fact has worried many scientists ______the Earth is becoming warmer and warmer these years.
A. what B. which
C. that D. though
高二英语单项填空简单题查看答案及解析
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It’s obvious that she ______ him for a long time．
A．has adored B．adored
C．is adoring D．has been adoring．
高二英语单项填空中等难度题查看答案及解析
or why 7,000 should drown or 55,000 die in their cars. No one establishes a quota (定额) for each type of death. It just happens that they follow a consist
ent pattern year after year.
the Western world have remained strangely static throughout the whole of the century, despite all the technological advances and increases in safety standards that have happened in that time. Wilde developed an interesting theory called “risk homeostasis”. According to this theory, people naturally live with a certain level of risk. When something is made safer, people will get around the measure in some way to get back to the original level of danger. If, for instance, they are required to wear seat belts, they will feel safer and thus will drive a little faster and a little more recklessly, thereby statistically canceling out the benefits that the seat belt offers. Other studies have shown that where a crossing is made safer, the accident rate invariably falls there but rises elsewhere along the same stretch of road as if making up for the drop. It appears, then, that we have an inborn need for danger. In all events, it is becoming clearer and clearer to scientists that the factors influencing our lifespan are far more subtle and complex than had been previously thought. It now appears that if you wish to live a long life, it isn’t simply a matter of paying attention to certain precautions such as eating the right foods, not smoking, and driving with care. You must also have the right attitude. Scientists at the Duke University Medical Center made a 15-year study of 500 persons personalities and found, somewhat to their surprise, that people with a suspicious or mistrustful nature die prematurely far more often than people with a sunny disposition. Looking on the bright side, it seems, can add years to your life span.