A good disguise keeps you hidden, right? Well, sometimes the best disguise is actually the most dazzling because research reveals that flashy metallic iridescence(金属彩虹色) can visually puzzle predators, which allows colorful prey to survive another day. Those surprising results appear in the journal Scientific Reports.
Shining iridescent color, which changes depending on the angle from which it's viewed, is favored by everything from birds to beetles and blossoms to butterflies.
“And in our research group we are of course interested in why this vivid metallic color is so widespread in nature.” Karin Kjernsmo of the University of Bristol adds that in some cases the showy splashes of light are a sexual strategy. “Here I would like to point out that in some species, particularly those that display strong sexual dimorphism(雌雄两性), such as birds of paradise or some butterflies or fishes, the occurrence of iridescence is most likely driven by sexual selection. For example, in many of these cases it is the males that have these vivid iridescent colors and they use them in mate choice or they use them as a signal to attract mates.” But iridescence also shows up in situations where reproduction is not an issue. “So what we are studying now is whether natural selection imposed by predation(捕食行为) could explain the occurrence of iridescence in prey animals.”
The idea that eyecatching colors could be used as a coverup isn't a new one.“The father of camouflage theory, Abbott Thayer, really believed that iridescence should be categorized as a camouflage strategy. And he wrote in his famous lifework ConcealingColoration in the Animal Kingdom, already in 1909, that ‘brilliantly changeable or metallic colors are among the strongest factors in an animal's concealment’. And this sounds like a completely unreasonable thing to say, because how can colors that are both brilliant and changeable contribute to animal's concealment？”
“In a similar way, we were asking whether iridescence, due to its changeability, could work as a form of camouflage by preventing shape recognition.” Kjernsmo and her colleagues trained bumblebees to associate a particular shape—a circle or an oval—with a sugar reward. And they found that the bees, when given a choice, would preferentially visit the shape they knew to be sweet. But when the shapes were iridescent, the bees had trouble telling them apart. “It seemed that the strikingly iridescent surfaces on our targets visually broke up the otherwise recognizable shape of the targets, which made them hard to distinguish.” As for making use of this method for hiding in plain sight, “Any practical applications is of course directly linked to any industry that has an interest in camouflage, that is how to conceal objects or make them more difficult to recognize.” The researchers are currently conducting experiments with birds, which often prey on iridescent insects to see if it helps to have a bird'seye view.
1.According to the passage, iridescence is not made use of by animals to ________.
A. live a little longer by escaping their predator(捕食者)
B. catch the attention of their mates
C. conceal themselves when in danger
D. catch sight of more colorful preys
2.From the study in the last paragraph, we can learn that ________.
A. Bees can always tell the difference between a circle and an oval
B. Bees are creatures that are fascinated by sweet things that are iridescent
C. If a circle, with a sugar reward, is iridescent, the bees may have difficulty finding it
D. Bees are likely to prefer circles to ovals, whether they are iridescent or not
3.What will be talked about in the following paragraph?
A. Whether there are any differences between bees and birds.
B. Some industries that have great interest in camouflage.
C. Why birds are not effected by iridescent insects.
D. Which camouflage theory applies more to birds.
4.Which of the following might serve as the best title of the passage?
A. A famous camouflage strategy B. Metallic iridescent as the best disguise
C. Colors unique to animals D. Shining colors as a sexual strategy
You know those nutrition guidelines the government issues every few years? It turns out that following them isn't just good for your health. It's good for the planet, too.
“What we found is that impacts vary across nations, but in the highimpact nations, in general, you can see that, if you follow a nationally recommended diet, despite the fact that these diets don't mention explicitly—or most of them don't explicitly mention—environmental impacts, that you are going to have lower environmental impacts due to that. So that's sort of fairly clear across all the highincome nations.” said Paul Behrens, an environmental scientist at Leiden University in the Netherlands.
The food we eat takes a big toll on the environment. A third of the icefree land on Earth is used for agriculture, and according to some estimates, producing food accounts for roughly a fifth of all humancaused greenhouse gas emissions. Fertilizer runoff also leads to other problems, like the algae blooms in Lake Eerie and the Dead Zone in the Gulf of Mexico.
However, following dietary guidelines would reduce those impacts, especially in wealthy countries like the US. “Most of the reductions come from meat and dairy，” which have an outsized impact on land use and pollution, and are a major source of greenhouse gases.(That's partly due to cow farts. Seriously.) Following the suggestions would also mean eating fewer calories, since many people here eat more than they need.
Overall, in highincome countries, Behren's team estimates that following the rules could result in as much as a 17 percent reduction in land use, a 21 percent reduction in nutrient pollution, and a 25 percent drop in agricultural greenhouse gas emissions. Cutting down on how much food we waste—which is roughly a third in the US—could help even more. The results are in the Proceedings of the National Academy of Sciences.
Of course, people are notoriously bad at following diets. But: “These nationally recommended guidelines do actually have a knockon effect on other areas of policy making. So if I'm developing a new healthyeatingforschools program then that's going to be based off a lot of detail that I get from the nationally recommended guidelines. So while it might not necessarily be the case that people follow directly … they actually are quite influential on the preparation of other advice.”
It seems that a smaller environmental footprint and a healthier lifestyle could go hand in hand.
1.Which of the following statement will Paul Behrens approve of?
A. Following a nationally recommended diet can have similar impacts in different countries.
B. Following a nationally recommended diet can do good to our health.
C. Not all the countries have recommended diets in an explicit manner.
D. Some highincome nations don't mention the diet explicitly for its impacts can be ignored.
2.What do the underlined words “takes a big toll on” in paragraph 3 probably mean?
A. shows signs of B. has a bad effect on
C. takes full advantage of D. makes up for
3.Which of the following is TRUE according to the passage?
A. Food production can lead to about 20 percent of humancaused greenhouse gas with only a third of the icefree land used.
B. It is estimated that following dietary guidelines can lead to decrease in more land use than in nutrient pollution.
C. Paul Behrens' new program concerning healthy eating for schools is likely to be based on national nutrition guidelines.
D. Some wealthy countries tend to reduce meat and dairy though the other areas of policy making isn't effected much.
New York City is a world capital in every sense of the word—it's a cultural and economic powerhouse, and arguably the most influential city on the planet. But it wasn't always this way, as the following cities once dominated the world around them.
DjenneDjenno
In the flood lands of the Niger delta people have been building houses and other structures with clay for centuries. The town of DjenneDjenno is made entirely out of clay. It was inhabited as far back as 250 BC, and became an important link in the transSaharan gold trade(跨撒哈拉黄金交易). Constructed on hills called “toguere”， the city managed to escape the marshy(沼泽的) landscape and annual floods produced by the rainy season. DjenneDjenno is believed to be one of the earliest settlements in the subSaharan region, and is considered by some to be “the typical African City”.
Archeological evidence shows us a continuous human presence in the area up until the 14th century AD, when people moved to the nearby town of Djenne, founded in the 11th century. Further evidence points out that even before the city's construction, the Bozo people were growing wild rice in the region. In the 13th century AD, with King Koumboro's conversion to Islam, its palace transformed into a mosque.
Carthage
Legend has it that Carthage was founded by Queen Dido of the Phoenicians. She fled the city of Tyre located in presentday Lebanon in order to escape the hatred of her brother Pygmalion, who was her rival to the throne. Along with a group of settlers, she traveled a great distance by sea and landed in North Africa, where she met King Iarbas. He offered to give them land in order to build a settlement, but no bigger than the surface covered by the hide(牛皮) of an ox. They cleverly cut the hide into thin strips and were able to enclose a fairly large area of land. On this land, the mighty city of Carthage was built.
These stories are most likely just that, but the fact that the Phoenicians built the city around 760 BC is true. Located in such a good position—in the middle of the Mediterranean, close to Sicily, Sardinia and Corsica, and a pretty good distance from Egypt—helped make Carthage a leading trade center and military power. The population soon reached half a million citizens and, in order to house them all, buildings were all built five or six stories tall. Carthage was the first city in ancient times to have a centralized sewage system, linking all buildings within the city walls. The most notable of structures among the ruins was the “Thophet”， which is believed to be an altar(圣坛) for child sacrifice.
Tenochtitlan
Tenochtitlan was the capital city of the Aztec Empire. It was built on an island surrounded by Lake Texcoco deep inside the jungles of Central America. By the time the Spanish conquerors were aware of its existence, the population was around 200，000. This was a city very different from what the Europeans were used to. Founded in 1325 AD, the Aztec capital was joined to the mainland by three causeways(堤道). It was laid out in straight street grids and had enormous pyramids at its center, which were surrounded by the skulls of the dead and ceremonial sculptures.
1.What do we know about the ancient cities?
A. Tenochtitlan was the first city to link all buildings within the city walls using a centralized sewage system.
B. Carthage was considered to have played an important role in the transSaharan gold trade.
C. There was no doubt that Carthage was founded by Queen Dido of the Phoenicians.
D. According to some people, the city DjenneDjenno is “a typical African city”.
2.The passage is most probably taken from ________.
A. a news report B. a science fiction C. a history book D. a research paper
My mother and her family kept information about my father and his family a secret from me for over half a century. In 2010 I began to ______ my father through Ancestry.com. However, I learned he had ______ cancer on August 6, 1999 in a hospital in Dallas, Texas.
When I got my father's death ______， the medical examiner told me because my father had no ______ around the city, they buried him in a body bag in a(n) ______ grave in an old cemetery.
I knew my father ______ in WW2 so I decided to work on getting his remains ______ to my state to be buried in our national cemetery. From 2011 to 2017 I kept working on ______ my debt from a divorce and increasing my ______ score so someday I could get a personal loan.
That certificate of ______ service proved my father served 43 months in WW2 in the USA Army Air Force fighting the Nazi's. I still did not have the money ______. In July of 2018 a bank approved a $10，000 personal loan so I had a funeral director ______ a permit to exhume my father. After 4 months of ______ I asked Senator Brown for help again in November. Six days after he contacted Texas officials a permit was ______.
On July 9, 2019 an airplane will ______ at the Cleveland Hopkins International Airport ______ I will be finally ______ with my father and touch his metal casket and the missing piece of my heart will be ______.
On January 10, 2019 the Ohio Patriot Guard Riders will escort my father's hearse through my ______ to be buried with honors in our states National cemetery and one day in January Senator Brown will have an American Flag ______ over our Nation's Capital to honor my father.
If you never give up one day your dream will become a reality.
1.A. hire out B. allow for C. search for D. dive in
2.A. suffered from B. died of C. evolved into D. died from
3.A. adjustment B. diploma C. penalty D. certificate
4.A. soldiers B. seniors C. relatives D. enemies
5.A. unprotected B. unmarked C. theoretical D. mobile
6.A. joined B. played C. served D. enrolled
7.A. brought down B. brought in C. brought out D. brought back
8.A. lowering B. increasing C. wiping D. swapping
9.A. housing B. employment C. marriage D. credit
10.A. sustainable B. military C. authentic D. historic
11.A. moreover B. while C. though D. therefore
12.A. apply to B. apply for C. try out D. try on
13.A. clarifying B. waiting C. requesting D. wrestling
14.A. suspended B. rejected C. granted D. substituted
15.A. land B. stop C. leave D. touch
16.A. which B. whose C. where D. when
17.A. confronted B. reunited C. involved D. occupied
18.A. reserved B. restricted C. restored D. rewarded
19.A. school B. church C. country D. hometown
20.A. flowed B. flown C. covered D. controlled
—Oh, Hannah just told me that she was unable to translate the report into English.
—________？She once spent 10 years living in London.
A. Guess what B. Why not C. So what D. How come
________ the concert to raise money for hunger relief and to make the public aware of the problem, Geldof invited many famous musicians to take part in it.
A. Intended B. Intending C. Having intended D. To intend
