1 . Jackdaws (寒鸦) switch between two sets of flocking (聚集) rules with differing results, new research has found. Flocks flying to winter roosts (居住地) are orderly no matter how many birds they contain; those trying to fight off enemies are initially disorganized when their numbers are small and then suddenly flip to order once enough birds join in.

Swimming bacteria, marching locusts, schooling fish and flocking birds all function as units. This phenomenon can emerge when individual agents following the same rules come together, says Alex Thornton, who studies cognitive evolution at the University of Exeter in England. “We got used to thinking of collective behavior as this almost physical phenomenon,” he says. “So the idea that animals might actually change the rules that they use when their environment and what they’re trying to achieve are different is quite novel and exciting.”

The researchers filmed flocking wild jackdaws in Cornwall, England, with four high-speed cameras, charting individuals’ positions and flying courses. Of the 16 flocks recorded, six were “transit flocks”— jackdaws returning to their roosts on winter evenings. In these groups, regardless of size, each jackdaw adjusted its course based on a fixed number of neighbors and always maintained order.

To initiate “mobbing flocks,” the researchers presented to groups of jackdaws a fake fox holding a fake, flapping bird and played alarm calls that the birds commonly use to warn other birds against enemies. In this context, jackdaws instead navigated by tracking all birds that were within a fixed distance. “With these rules, you have emergence of order from mess,” Thornton says. “Small flocks are disorganized. When the density of the flock reaches a certain level, suddenly there is order — much like how a gas transitions into a liquid.” These transitions have never been observed in birds before, he adds.

“What our work shows is that you cannot ignore the external environment in trying to model collective behavior in biological systems,” says Nicholas Ouellette, a physicist at Stanford University and co-author on the study. Drawing inspiration from jackdaws, he says, engineers could someday use context-dependent responses to build teams of drones that work together for firefighting, surveying and search-and-rescue missions: “It allows you to think about designing systems that are more flexible, that can change the rules to make the behavior more proper.”

1. What does Alex Thornton’s new research find about Jackdaws?

A．They vary the rules with which they gather.

B．They function as units while flying to winter roosts.

C．They tend to fly apart when meeting with enemies.

D．They get disorganize to wait for more birds to join in.

2. Which of the following statements is true of “transit flocks”?

A．They are normally big in size.

B．They are always in good order.

C．The members seldom changed their courses.

D．The members find direction by tracking faraway birds.

3. It can be inferred from the passage that the transitions of a gas into a liquid are processes in which ________.

A．mess turns into order

B．density remains the same

C．changes often happen slowly but steadily

D．molecules keep a fixed distance from each other

4. Nicholas Ouellette is quoted in the passage in order to ________.

A．highlight the flexibility of flocking birds

B．reveal how context-dependent responses occur

C．show how the research findings can be applied to different fields

D．call attention to the importance of the external environment

2 . The night sky has been an endless source of fascination since the start of human history. For example, the mysterious large-eyed, bronze statues of the ancient Shu Kingdom, discovered at the Chinese archeological site at Sanxingdui, were believed to have been able to look across great distances into the stars. In reality, humans can see very little of the night sky with the naked eye. And, for a long while, people were unable to understand what they could see.     1    

Our power to investigate and thus understand space changed dramatically when the first telescope (望远镜) was angled at the night sky, increasing as it did the power of the human eye and enabling us to understand that the universe is far larger than was previously imaginable. The planets were seen to be worlds similar to our own, many of them even having their own moons.     

    2     Some 300 years later, we learnt that the Milky Way itself was just one galaxy among billions of others, spread across the blackness of space like great islands of light and matter floating in a vast cosmic ocean.

Almost 400 years after the first Earth-based telescope was invented, the Hubble Space Telescope was launched into orbit, giving astronomers indeed all of us — the first breathtakingly beautiful images of our universe taken from beyond Earth.     3     It has also helped us to work out the age and nature of the universe, and discover the incredible fact that the universe is expanding at an ever-increasing speed.

    4     Currently, China operates the world’s largest and most powerful radio telescope, the FAST telescope, completed in 2016. The 500-metre dish of the “Eye of Heaven”, as it is known, is being used in the search for dark matter. This vast dish also has the ability to explore regions of space billions of light years away, right at the edge of the visible universe.

A．The success of the Hubble has depended on teams of engineers, technicians, scientists, and astronauts working together on high performance challenges for the cause.

B．Soon, it was understood that the Sun was just one star among billions in the galaxy we call the Milky Way.

C．Not knowing what the stars were, people in ancient times used their imaginations to create a world in the sky.

D．To see even further into the universe, many countries are now engaged in building ever more advanced telescopes.

E．So much of the Milky Way remains unexplored that we are still close to the start of this incredible journey of discovery.

F．Nothing in history has allowed us to see so much over such great distances, from clouds of gas where stars are being born to new planets where we might find life.

3 . As summer ends, fresh starts abound

So, after a late short blaze of summer, autumn is here. The trees will soon be in their autumn beauty, sweet fragrance waving in the air.     1     . Trees bend beneath the thick clusters of ripe fruit, which bows their branches to the ground; and the corn, piled in graceful bundles, coloring the landscape with a golden hue.

The ultimate celebration of the season in English is arguably Keats’s “To Autumn” - “Season of mists and mellow fruitfulness / Close bosom-friend of the maturing sun” - which was written after a Sunday walk in harvest time. “How fine the air,” he wrote to his friend JH Reynolds, “    2     Somehow, a stubble-field(残梗地)looks warm - in the same way that some pictures look warm.”

    3    . That is between stubble and warmth and the simultaneity of death and life autumn unfolds. The days grew shorter down to a precious few, which catches at the essence of this time.

Autumn is more subtle than summer, less over-determined. It is full of beginning, too. Every for those who now have nothing to do with schools there is sense of starting again - new book; new clothes, new thoughts.     4    . Leaves will return to Earth, and Female more trees.

What feels like falling (pine cones, acorns, conkers, leaves) is also about starting again kind of - to use Alice Oswald’s lovely phrase - falling awake. Even though the season is the to winter, somehow, the world knows that winter is necessary, and the long preparation for the of winter is a beautiful, necessary part of the world. So yes, autumn is here. And that is cause for celebration.

A．There is something about noting that contradiction.

B．I never liked stubble-fields so much as now - Aye, better than the chilly green of the spring.

C．There is a harmony in autumn, and a shine in its sky, which through the summer is not heard or seen.

D．Abundance is everywhere: berries; apples, pears, pumpkins, squashes, all the grains.

E．Fallen leaves lying on the grass in the November sun bring more happiness than the daffodils.

F．Berries are food for wildlife - and then seeds on the ground, to grow into new plants next year.

4 . 选用适当的单词或短语补全短文。

A.medical       B.relieve       C.shelter       D. growing       E. alternative       F. doubled       G.fantastic       H.marketing       I. present       J. conducts       K.practically

More and more cats and dogs are getting the human treatment. There are pet spas, pet therapists and pet clothes. And the latest trend is pet hospices(临终关怀医院)。

Around the United States, a growing number of vets are offering hospice care and       1    it as a way to give pets ---and their owners---a less anxious, or comfortable passing. The approach, in the spirit of the human variety, involves stopping aggressive     2     treatment and give painkillers and anti-anxiety drugs. Unlike in hospice care for human, euthanasia(安乐死) is a(n)     3    ---and in fact, is a big part of this end-of-life care. When it’s time, the vet    4    it in the living room, bedroom, or wherever the family feels comfortable.

It’s part of a vet’s job to     5     pet owners’ guilt, give them an emotional bridge to their pets’ death and let them grieve at home---rather than in a clinic or animal     6     . The closeness    7    costs 25 percent or more than euthanasia in a clinic, but vets and their clients say it can be worth it.

“They’re in their own environment, not only the pets but the owners as well,” said Dr. Gardner, co-founder of Lap of Love, one of the leaders in this small but     8     market, “Other people and pets are welcome to be     9     . I’ve been to some houses where the owners had barbecues for the dog and invited me and the neighbours. The dog was the man of the hour.”

Dr. Michele Price, a vet in Northern Virginia whose in-home hospice care business has     10     since 2009, got a call about a Labrado named Champ. The dog had received per hospice care for months until recently, when he took a sharp downward turn. Before Dr. Price set up for the euthanasia, pet owners hugged Champ on a quilt next to the fireplace and told him what a good dog he was. As for Champ, “He fall asleep. That was the last thing he remembered.”

5 . Directions: Fill in each blank with a proper word chosen from the box. Each word can be used only once. Note that there is one word more than you need.

A. hike       B. requires          C. hosts          D. man-made       E. attraction      F. Belonging   G. peak   H. introduce   I. romantic     J. fascinating     K. sun-bathe

Touring “Treasure Island”

Chinese mainland tourists will be able to visit Taiwan via charted flights in July according to two landmark agreements signed on June 13. So, 21^st Century invited two young Taiwanese to     1     their favorite site on the island.

Yangming Mountain, north of Taipei

Young couples can definitely enjoy a     2     evening on the mountain and a bird’s eye view of the Taipei city. College students often visit the mountain for a     3    : others ride motorbike to the top. The mountain and the nearby town of Pei-tou have many hot springs, which often appear in romantic Taiwan TV dramas.

Ali Mountain, Jiayi County

Ali Mountain is the general name for 18 hills. The highest     4     of Ali Mountain is Tower Hill, which has a height of 2,663 meters. Ali Mountain is famous for its “five rare sites” - the sunrise, the Ali mountain Forest Railway, the famous Alishan Sacred Tree, the Grand Sea of Clouds and the Flamboyant Cherry Blossom. The best time to visit the     5     scenery is during the comfortable midsummer.

Taipei 101 tower, Taipei

The 101-floor landmark is one of the world’s tallest completed skyscrapers. Besides the shops inside and outside the tower, Taipei 101     6     splendid firework shows during festivals. A new     7     next to the tower is under construction. It will be a     8     beach on which the public will be permitted to     9    .

Dr. Sun Yat-sen’s Memorial Hall and Chiang Kai-shek Memorial Hall, Taipei

The squares in front of these halls are open all day to the public. They have become a paradise to colleges students, who often meet there for an activity that     10     space. You will run into students dancing, rehearsing skits or even playing musical instruments.

6 . As Climate Changes, Global Inequality Worsens

Scientists have long predicted that warmer temperatures caused by climate change will have the biggest impact on the world’s poorest, most vulnerable people. New research now indicates that this has already happened over the last several decades.

A study published this May in the Proceedings of the National Academy of Sciences found that in most poor countries, higher temperatures are more than 90% likely to have resulted in decreased economic output, compared to a world without global warming. Meanwhile, the effect has been less dramatic in wealthier nations - with some even potentially benefiting from higher temperatures.

“We’re not arguing that global warming created inequality,” says Noah S. Diffenbaugh, the author of the study and professor at Stanford University who studies climate change. But “global warming has put a drag on improvement.” The countries most likely to have lost out economically as a result of warmer temperatures have done the least to contribute to the problem, he adds.

Higher temperatures affect economic output in a variety of ways. For example, labor productivity decreases with extreme heat, crops produce lower yields and cognitive functioning declines.

The new study builds on past research, including a landmark report released last fall from the Intergovernmental Panel on Climate Change, the UN’s climate science body. The report showed that if global temperatures rise more than 1.5℃ by 2099, poor countries will likely face critical challenges, including the destruction of entire communities and millions of premature deaths.

Climate policymakers have tried for years to address the problem of the poorest countries facing the worst effects of rising temperatures. These countries were not generally responsible for global warming. Early attempts at addressing climate change internationally included different expectations for emissions reduction based on each country’s level of development. Poorest countries received more leeway (自由行事的空间) while the richest were set stricter targets.

But in some ways, that approach backfired (起反效果), especially in the U. S. It helped feed the popular narrative that Washington is overpaying for climate change mitigation, while poorer countries are away with doing less. That conservative viewpoint has done some damage. Hardline distinctions between carbon reduction targets for rich and poor countries have been softened in recent years, in favor of a lighter version of what climate change policymakers refer to as “common but differentiated responsibilities.” That principle suggests that richer countries should bear a greater burden in addressing climate change, but remains vague about what that means for concrete policy.

Many of the world’s developing countries have cried foul. “This problem is created somewhere else,” Abdur Rouf Taiukder, Bangladesh’s Finance Scretary, told TIME in a recent interview. “We are spending more on adaptation because we have to live.”

1. Which of the following statement is true about the study published in May?

A．It warned the world about a speedup in global warming.

B．It explained a wider wealth gap between poor and rich countries.

C．It predicted a future where wealthy countries will benefit from climate change.

D．It pointed out that climate change has already caused the least developed countries to suffer.

2. Climate change affects a country’s economy in all of the following ways EXCEPT that it _________.

A．leads to extreme heat that has disastrous effects on agricultural output

B．results in higher temperatures which cause workers to be less productive

C．causes people to become less efficient in learning and other intellectual activities

D．is the direct cause of unbalanced development of the most and least developed countries

3. The underlined word “mitigation” in paragraph 7 probably means _________.

A．description

B．reduction

C．consumption

D．interaction

4. We can infer from the article that _________.

A．climate policymakers from developed countries have reached an agreement on how to address climate change.

B．many Americans are against the uneven division of the responsibility for addressing climate change among countries

C．there has been a lack of clarity in whether the poorest countries should share any of the burdens that climate change has put on the world

D．the less developed countries in the world have refused to spend any money in dealing with climate change

7 . 语法填空

Landslide injures at least 10 in Norwegian Town of Ask

A landslide (山体滑坡)    1    (smash) into a residential area near the Norwegian capital at midnight on Dec 30, which injured at least 10 people, left 21 unaccounted for and    2    (destroy) several homes, authorities said. By yesterday afternoon, according to a local official, about 700 people    3    (bring) to safety for fear of further landslides.

The landslide    4    (cut) across a road, which left a deep gap that cars could not pass. Video footage showed dramatic scenes including houses falling into the gap.

Rescue teams worked day and night to search the area for people caught in mud and debris. “People’s life is the most valuable and is worth    5    (pay) the most attention to”, they told the press.

The area where Ask    6    (locate) is known to have a lot of quick clay, and the clay can change from solid to liquid form. Previous landslides have been reported in the region. In the future, the local weather bureaus should make sure they    7    (warn) people of any possible danger in advance.

8 . Directions: After reading the passage below, fill in the blanks to make the passage coherent and grammatically correct. For the blanks with a given word, fill in each blank with the proper form of the given word; for the other blanks, use one word that best fits each blank.

Boyan Slat, a Dutch inventor is cleaning the world’s most polluted rivers in an effort to save the oceans. He has made it his mission    1    (remove) plastic from the oceans. His organization, The Ocean Cleanup, has successfully started to clean the pollution that has been circling in the Great Pacific Garbage Patch. But millions more tons of plastic enter the oceans every year, almost all of it     2     (flow) from rivers.

Just 10 rivers are responsible for around 90% of all that plastic,     3    a 2017 study from the Helmholtz Centre for Environmental Research. “So     4    we focus on the worst rivers, we believe we can really have the fastest and most cost-effective way to close the tap and prevent more plastic from reaching the oceans in the first place,” Slat said.

The Ocean Cleanup is effectively using floating trash collectors called “Interceptors”. These solar-powered, autonomous systems use the rivers’ currents to guide the trash onto a conveyor belt that carry the waste to     5     (await) bins.

The first interceptor went to work in Jakarta, Indonesia, to pull plastic from a waterway called the Cengkareng drain. A second interceptor began collecting trash flowing down the Klang river in Kuala Lumpur, Malaysia. On the other side of the world,     6    Interceptor has recently started removing river pollution near the mouth of the Rio Ozama in the Dominican Republic.

“    7    the river is polluted, the fish die. Every year there are less fish,” Luis Peguero, a local fisherman, explained. When Peguero is lucky enough to reel in (收线拉起) a catch, it     8    not be safe for his family to eat. “You find stuff in the fish, especially the catfish. Trash, bottle lids, even a shoe. The fish can’t survive this,” said Peguero. To him, the modern trash-collecting catamaran (双体船) is a peculiar but welcome sight.

The Ocean Cleanup is working with the local governments and communities to help retrieve (取回) the plastic the Interceptors collect. “By stopping plastic in rivers, we hope to not only address the big global plastic pollution issue, but also really help make life better for the people    9    live near these problematic rivers,” said Slat.

The Ocean Cleanup’s goal is to tackle the thousand most polluted rivers within 5 years. Soon interceptors     10     (head) to Vietnam, Thailand, Jamaica and Los Angeles County in the United States.

“We are getting out tons of plastic every single day,” Slat said. “We accept that we won’t deliver magic in one go. But we’re doing this, step by step.”

9 . In 1969, a ship carrying 90 passengers arrived in Antarctic waters. Since then, Antarctic tourism has increased noticeably. Nowadays, over 35,000 visitors a season came to the Antarctic during summer, with the intention of visiting colonies of penguins.

That worries many environmentalists, who fear such quantities of people may be disturbing the penguins. However, a study published in Polar Biology by Maureen Lynch of Stony Brook University brings good news for penguins, tourists and tour-operators alike – for the tourists’ visits are not stressing the birds at all.

The conventional way of deciding whether visits by tourists are stressful to the animals is to recruit a bunch of PhD students to observe those animals and make a number of behavioral observations when tourists are and are not present. This is difficult and expensive, for even PhD students need to be housed and fed. Another choice is to sample the animals’ blood and analyze it for stress hormones. The problem with this is that catching animals to measure their hormone levels is stressful.

There is, however, a third way, which is to look for stress hormones in animals’ droppings (排泄物). Dr. Lynch knew from previous work by her partner that some stress hormones show up in penguin wastes, and that hormone concentrations in droppings went up shortly after animals were approached by human beings, and then returned to normal later. With that in mind, she decided to compare droppings from penguin colonies visited by lots of tourists with those less visited.

As the researchers expected, all collected samples contained related stress hormones. Contrary to their expectations, however, there were no significant differences between samples from different sites, regardless of the number of visitors those sites played host to. It seems, then, either that penguins do not worry about human visitors in the first place, or that they quickly get used to them. What is more, Dr. Lynch’s method provides an easy way to monitor the situation. If a growing number of tourists put the birds under stress, it will be possible to advise tour operators to consider their business at less-visited colonies.

1. What do we know about Antarctic tourism?

A．It enjoyed popularity in 1969.	B．It attracts visitors in all the year round.
C．It allows people to see penguins.	D．It had disturbed the penguins.

2. The problem of the conventional method lies in ________.

A．the difficulty in recruiting PhD students	B．high costs required in the Antarctic
C．comparison of penguins’ behaviors	D．the huge trouble of catching animals

3. What did Dr. Lynch’s partner find about penguin waste?

A．It contained certain stress hormones.	B．It had high level of stress hormones.
C．Its hormone level was unstable.	D．Its hormones were at normal levels.

4. What can we learn from the analysis of the collected samples?

A．Penguins are afraid of visitors.	B．Penguins are used to visitors.
C．Penguins are hardly stressed by tourists.	D．Penguins are always under great stress.

10 . Directions: Read the following passage. Summarize the main idea and the main point(s) of the passage in no more than 60 words. Use your own words as far as possible.

Effects of Acid Rain

After studying the Hubbard Brook Forest and other areas, researchers found several important effects of acid deposition, more commonly referred to as acid rain, on both natural and man-made environments. Aquatic (水生的) settings are the most clearly affected because acidic precipitation falls directly into them.

As this acidic liquid flows into larger bodies of water, it is diluted (稀释). However, over time, acids can increase and lower the overall pH of the body of water. Acid deposition also causes clay soils to release aluminum and magnesium, further lowering the pH in some areas. If the pH of a lake drops below 4.8, its plants and animals risk death. It is estimated that around 50,000 lakes in the United States and Canada have a pH below normal (about 5.3 for water). Several hundred of these have a pH too low to support any aquatic life.

Aside from aquatic bodies, acid deposition can significantly affect forests. As acid rain falls on trees it can make them lose their leaves, damage their bark, and stunt their growth. By damaging these parts of the tree, it makes them vulnerable to disease, extreme weather and insects. Damage to forests by acid rain is seen all over the world, but the most advanced cases are in Eastern Europe. Half of the forests in Germany and Poland and about 30 percent in Switzerland, are estimated to have been damaged.

Finally, acid deposition also has an effect on architecture and art because of its ability to corrode certain materials. As acid lands on buildings (especially those constructed with limestone), it reacts with minerals in the stones, sometimes causing them to disintegrate and wash away.

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